Last month I went to see X-Men: First Class. It was pretty good, though less because of the story itself than because of Michael Fassbender's magnetic presence as … Magneto. The action was set in the early 1960s, during the Cuban missile crisis, when John F Kennedy told the Soviet Union that if they tried to put nuclear weapons in Cuba, just 90 miles off America's coast, there would be hell to pay. Possibly a third world war.

As everyone has such itchy trigger fingers, it fell to the X-Men, a motley crew of insecure, untested kids, to keep the Russians and the US from blowing up the planet. In the end, they achieved their objective, sparing mankind the unspeakable horrors of a nuclear winter – but not before the crippling of James McAvoy, whose character, Professor X, had been played in the earlier X-Men movies by Patrick Stewart. This was one thing that puzzled me about the new film. How does a character played by the bland, annoying McAvoy later mature into a character played by the intense, chiselled, charismatic Stewart? It's like casting Zac Efron as the young Sean Connery. Isn't it?

But I digress.

While I was waiting to see X-Men, my cineplex showed a preview for Green Lantern, the film where Ryan Reynolds plays a callow, untested youth who has to prevent huge, unscrupulous extraterrestrial machines from blowing up planet Earth. Needless to say, Green Lantern did save the planet. But by a strange coincidence, right after the trailer pitching Green Lantern, the theatre aired a preview for Transformers: Dark of the Moon. This is the third in a series of loud, stupid movies in which the Smurf-like Shia LaBeouf has to prevent interloping extraterrestrials called decepticons from blowing up the planet. Good luck, Shia!

But perhaps the strangest thing of all was that just before the X-Men film began, the theatre showed yet another preview, this one for Rise of the Planet of the Apes. This is the long-awaited prequel to the original Planet of the Apes, in which Charlton Heston returns from a mission in outer space to discover that Earth has been taken over by apes. Incredibly smart, gifted, voluble apes, but apes all the same. Creatures that ought to be smart enough to know that a film chronicling their insurgency should be called Rise of the Apes or Planet of the Apes: First Blood but not Rise of the Planet of the Apes, as this literally makes no sense. But I digress.

All this obsessing about intergalactic mayhem is kind of weird. Movies usually reflect the neuroses and submerged fears of society: that politicians are corrupt, that men are ruthless predators, that Madonna might make another movie. But I don't think the planet's imminent destruction is high on our list of concerns. Right now, I think we're all worried about jobs, healthcare, inflation, our savings getting wiped out, crime, disease, the future of our unborn children, al-Qaida, and maybe even the rise of neo-fascist movements in Scandinavia and eastern Europe. But I don't think that many of us are terribly concerned about hi-jinks concocted by intransigent extraterrestrials or precocious simians. I just don't.

Naysayers can make the argument that escapism has always been an integral feature of motion pictures. But they cannot make the argument that exactly the same escapist fantasy has surfaced in movie after movie in the past. That's what makes this summer so different. Down through the years, there have always been silly, featherweight romps that took the public's mind off things such as the Great Depression and the rise of the Third Reich. Cary Grant, the greatest movie star of them all, spent the prime years of his career reassuring people that everything was going to work out all right in the end.

But not all the movies of the 1930s fell into the escapist genre. There were powerful films such as The Rules of the Game that dealt with serious issues including injustice, poverty, class war. In the 40s, there were raftloads of inspirational films, such as Mrs Miniver, which were about the need for everyone to pull together in dark times. Japanese films in the 1950s often dealt with the ravages of nuclear war; all those Godzilla flicks were expressions of Japanese horror at what had befallen their countrymen at Hiroshima and Nagasaki. In the 60s, film after film all over the world reflected fatigue and even disgust with traditional mores: movies as varied as To Kill a Mockingbird, In the Heat of the Night, Easy Rider, The Wild Bunch, Pierrot le Fou, Bonnie and Clyde, and The Graduate were about societies that were coming apart at the seams.

And it's worth pointing out that the job of addressing society's fears did not fall exclusively to artistes and auteurs whose films were only shown to snooty audiences in art houses; movies like Guess Who's Coming to Dinner and The Spy Who Came in From the Cold were made for general audiences. These films had mass appeal.

This tradition continued into the 70s, where brilliant films such as The Godfather II, The Candidate and Chinatown reflected the American public's distrust of their elected officials. American films turned profoundly cynical in the 70s, leading to films such as Apocalypse Now and The Conversation, and later, Full Metal Jacket, Platoon, The China Syndrome and Silkwood. At some level – not far below the surface – these films were consciously addressing issues that were on ordinary people's minds: war, corruption, drugs, America's "loss of innocence". The same pattern held true until well into the 90s, when serious films at least occasionally made their way into cinemas.

All this has changed as the target audience for movies has skewed closer to prepubescence. Movies today, particularly summer movies, are populated by camp superheroes who overcome insuperable odds to defeat evil. They are daft, interchangeable products aimed at teenage boys whose only direct experience of overcoming insuperable odds is to persuade their fathers to lend them the car to go to the multiplex.

There is nothing wrong with this. There is nothing wrong with releasing one movie after another that basically repeats the same theme that has dominated cinema since the dawn of the industry: the difficult but nonetheless inevitable triumph of David over Goliath, of good over evil. This, after all, is the theme of such worthy movies as The Adventures of Robin Hood, Casablanca, Gladiator, Ben-Hur, Shane, High Noon, Schindler's List, The Untouchables, Braveheart, Rocky, Star Wars, Jaws and even The Matrix. But these movies, while united by a common theme, do not share a common subject matter. Some of them are about the threat posed by Romans. Some are about the threat posed by Nazis. Some are about the threat posed by ranchers or gangsters or great white sharks. But not every one is about the apocalyptic threat posed to the inhabitants of planet Earth. They are not all about Armageddon. They are not all exactly the same movie.

What is the explanation for this deadly, dreary sameness? Here are a few theories. One, nothing succeeds like success in Hollywood, so if one movie about planet Earth going down for the count is successful, Hollywood will keep on making them until the audience literally walks out in disgust. Two, movies about the threat posed to earth by extraterrestrials – or apes, or giant worms, or tidal waves – do not require the disbursement of large salaries to movie stars. Three, recent movies that did deal with serious issues, such as the wars in Afghanistan and Iraq, flopped at the box office. It did not help that they were mostly terrible. Four, teenage boys really are more worried about marauding extraterrestrials than they are about war, fascism, inflation and terrorists. So it's only natural that Hollywood should address these concerns. A case can even be made that the only thing that scares teenage boys more than remorseless extraterrestrials is teenage girls.

A case can even be made – counterintuitive though it might seem – that these films do reflect the fears, dreams and neuroses of the movie-going public, including adults. Look at it this way: a real-life attack on Earth by intelligent machines or implacable monsters or cunning aliens or feisty apes would not be that big a deal; these are the kinds of dime-a-dozen threats mankind can handle with one hand tied behind its back. The collapse of the euro, on the other hand, has us stumped. A global recession that simply will not end – except in China – has us flummoxed. The realisation that inflight terrorism can never entirely be eliminated has us terrified. Maybe the reason we are seeing so many fanciful movies about the destruction of the planet is because most of us would actually prefer to confront a threat to the entire planet, rather than a threat to Greece and Ireland and Iceland and Portugal and our bank accounts and our kids and our 747. If martians attack, we can all pull together the way we did at Dunkirk and El Alamein and Stalingrad. But if the euro collapses … what then?

The final possibility is that Hollywood has simply run out of ideas. Since I saw X-Men, I have seen Captain America, a film about a mad Nazi scientist hellbent on the destruction of civilisation, and Cowboys & Aliens, a horse opera smorgasbord about a 19th-century extraterrestrial invasion. Gosh, couldn't someone please make a good old-fashioned movie such as Scarface or Psycho or Lethal Weapon 4? Where the villains come not from deep in outer space but from deep in the Caribbean or deep in East Los Angeles or deep in the basement?

Rise of the Planet of the Apes is released on 11 August, and Cowboys & Aliens on 17 August.