Exactly half a century ago on Wednesday, Martin Luther King described his dream, a dream in which "one day right there in Alabama little black boys and little black girls will be able to join hands with little white boys and white girls as sisters and brothers".

So it seems deliciously apt in terms of reflecting how race relations have progressed in the US since Dr King's era that, just a whisker short of the anniversary of his speech, the world bore witness to one of the more intriguing examples of cultural appropriation. Sadly, King omitted to say whether he also dreamed of "little white girls from Tennessee mimicking anilingus on little black girls wearing giant animals on their backs", so it's impossible to know how he would have reacted to Miley Cyrus' performance at the VMAs on Sunday. But it seems likely that not even he could have foreseen how the American celebrity world would manage to twist his image into something quite so, if not actually racist, then certainly race-ish.

As I watched Cyrus's performance on Monday morning on my laptop, the first floats in the Notting Hill carnival parade went by outside my window. I have lived in the middle of the carnival route for 12 years now and going by my wholly unscientific observation, the carnival is one of the lovelier forms of cultural cross-pollination. Yes, there are lots of white people trying to dance, not too appallingly, to reggae soundsystems, as well as an increasing overflow of aggressively drunk white men who seem to have got lost on their way to Reading festival. But in the main, the carnival is one of the closest adherents to King's dream that I have encountered in my four decades living in four different cities, with its happy celebration of African-Caribbean traditions, which most of the white attendees excitedly cheer along.

Which brings us back to Miley Cyrus' VMA performance – a perfect illustration of just how the celebrity world appropriates black culture and female liberation. The song Cyrus sang, We Can't Stop, was written by Timothy and Theron Thomas and given to Cyrus when she told them, presumably without a wince: "I want something that feels black." Instead of giving her something by, I don't know, John Coltrane, the Thomas brothers gave her a song originally written for Rihanna which, to be fair, was almost certainly the image of blackness Cyrus had in mind as I don't think Coltrane did much twerking.

Cyrus is hardly the first female celebrity to try to prove her maturity through sexuality and, to be fair to her, she probably felt that she needed more than a pixie haircut to compensate for the Billy Ray Cyrus factor. Whether that had to involve sticking her tongue out repeatedly as if Gene Simmons never happened is something only cultural historians will be able to chart later. Plenty of male singers grab their crotches while performing, but it seems to be only female singers these days who feel the need to strip down to their underwear and simulate sex acts on stage. As nice as it would be to imagine a world in which young women weren't taught to equate hypersexuality with maturity and independence, that remains as unrealised a dream as much of King's speech.

Cyrus, though, twerked the formula as well as her body by adding in a racial element while she copied the dance moves of strippers and bellowed her love of drugs. (Billy Ray's heart must be pretty achy breaky these days.) On stage as well as in her video she used the tedious trope of having black women as her backing singers, there only to be fondled by her and to admire her wiggling derriere. Cyrus is explicitly imitating crunk music videos and the sort of hip-hop she finds so edgy – she has said, bless her, that she feels she is Lil' Kim inside and she loves "hood music" – and the effect was not of a homage but of a minstrel show, with a young wealthy woman from the south doing a garish imitation of black music and reducing black dancers to background fodder and black women to exaggerated sex objects.

Cyrus's approach to cultural appropriation is as sophisticated as Robin Thicke's view of female sexuality, making it delightfully apt that they, inevitably, ended up duetting together. In a brilliant blogpost on the song, writer Wallace Wylie points out that while Thicke's song, Blurred Lines, doesn't endorse rape, as some have alleged, it does present the most tediously reductive view of sex and women with the idea of "a good girl" just needing to be liberated by alcohol and a penis to become "an animal". It's an idea that was satirised six years ago in SuperBad by teenagers and yet remains as credible in pop songs today as it does in porn. It's one of life's ironies that pop music is supposedly a progressive and young person's art form, yet the messages it sends are generally as retrograde as the gruntings of an embarrassing middle-aged uncle at Christmas dinner. It's downright bizarre that a carnival that celebrates its 50th anniversary next year should look so much more modern than anything in the pop world.

So like King, I too have a dream: I have a dream that female celebrities will one day feel that they don't need to imitate porn actors on magazine covers and in their stage acts. I have a dream that the predominantly white music world will stop reducing black music to grills and bitches and twerking. And I have a dream that stupid songs about seducing "good girls" will be laughed at instead of sent to No 1. And most of all, I dream that I never, ever have to see Miley Cyrus gyrating against Robin Thicke's crotch again. We won't be free then, but it will be a start.