The HTC 10 is by far the best phone I've ever owned. It has a colourful, sharp screen that, at 5.2 inches, is big without verging into unwieldy phablet territory, while the all-metal design gives it a premium feel. It's fast too, thanks to a Snapdragon 820 chip and largely untouched version of Android. Its camera excels in low light, the battery easily gets me through a day (extended Pokémon Go sessions not withstanding), and the powerful headphone amp is the best available on a mainstream device. I even like its slightly portly dimensions.

But would I say the HTC 10 is an exciting device? No. If anything, I'd say it's rather dull.

It's a problem that nearly all the big smartphone manufacturers face. That last great bastion of smartphone quality held by Apple—the camera—was matched, if not beaten by nearly all of this year's flagship devices. Even the OnePlus 3, a phone with a premium design and specs, which costs a mere £330/$399, stands toe-to-toe with phones costing twice as much, if not more. Cameras, screens, batteries, operating systems—they're largely the same across devices, and they're all very good. That's a great thing for consumers but not so much for smartphone makers used to charging a premium for the basics. It takes a special something to stand out.

Which is why we've started to see things like the LG G5, a phone that features an interesting, but largely useless expansion port for adding things like a beefier headphone output or a camera grip. Both of those modules were available alongside the G5 at launch in April, and it's rather telling that few have been released since. Motorola tried something similar with the Moto Z's lacklustre Moto Mods, creating a super-thin phone that allowed users to snap on a "backpack" with an additional battery, a DLP projector, or a speaker to the phone—all of which are probably better served by standalone devices.

That LG or Motorola tried something different isn't a bad thing—lord knows the smartphone market needs it—but they simply didn't go far enough. Trying to make a phone that appeals to a mass-market audience while also offering more-tailored customisation options was always going to result in a compromise to either the core device or the modules. In the case of the Moto Z, both parts suffered. It would be a far better idea to just ignore the mass market entirely—reserving it for separate line of reasonably priced devices—and go niche. Very, very niche.

Recently, I was invited to take a look at the Cat S60, a smartphone designed by UK OEM Bullitt but branded by Caterpillar, makers of all things yellow and digger-like for construction sites. Rugged phones are nothing new—Samsung makes one, and indeed Bullitt used to make one for Cat rival JCB—but what's striking is just how specialised the Cat S60 is. It is unashamedly massive, despite sporting a mere 4.7-inch display, and comes in at a whopping 12.6mm thick. Its design is less than subtle too, with a chunky die cast frame, bulky physical buttons, and all manner of flaps and switches.

And yet, there's something strangely compelling about the way the S60 looks. I like to think that, if Batman went into a shop to buy an Android phone, this is what he'd walk out with. The S60 feels incredibly solid; weighing a hefty 223g, it has the durability to match, being built to MIL-STD 810G standards, drop tested to 1.8m, and rated IP68 (completely dustproof, and waterproof at a depth of 5m for 60 minutes).

The chunky physical buttons, including the Android back, home, and task-switcher, are designed so that users wearing thick gloves can get to them, and even the touchscreen will work through gloves and underwater. Plus, there's a huge 3800mAh battery inside, which should last a while given the 720p display and midrange Snapdragon 617 SoC.

The Cat S60's niche trump card, though, is its built-in thermal imaging camera, which uses tech developed by Flir. It combines the image from the regular 13MP camera with thermal data from an IR sensor to create surprisingly clear thermal pictures, which show hot areas as shades of red and yellow and cooler areas as blues and greens. More importantly, it has multiple settings for taking temperature readings. For those in construction, building trades, or even emergency services, this is a fantastic feature.

Cat isn't under any illusions that the thermal camera in the S60 is 100 percent accurate—it typically comes within three degrees of a laser thermometer—but it still has plenty of uses. Gaps can be found in insulation during building work and electrical wires spotted when drilling through walls. Firefighters, who apparently are interested in the device, can use it before more accurate equipment arrives. Indeed, the sensor works well in smoke and gas filled environments, as evidenced by a demo where I had to find survivors (read: teddy bears with hot water bottles inside them) inside a smoke-filled room.

Yes, most people have absolutely no use at all for a thermal camera. But unlike the hideous projector attachment for the Moto Z or the camera grip for the LG G5, I'd argue that it's no mere gimmick either. The Cat S60, which costs about £530 in the UK ($599 in the US), is a specialised phone that has been designed for a very specific group of people, and for them it could prove genuinely useful. If Samsung suddenly decided to stick a thermal camera inside a S7 then it would be a gimmick—and it'd likely have a bunch of compromises attached to it too.

The point isn't that the Cat S60 is the greatest smartphone ever made—the screen isn't great, it's not the fastest device, and all the ports are covered in annoying flaps—but rather that it doesn't have to be. In chasing smartphone perfection, device makers have reached an impasse. It's time to stop aiming phones at everyone and start thinking about creating intelligently designed features targeting specific audiences. We all have things we value over others—headphone audio being my particular vice—and most people would happily pay a little more for a specific, uncompromised feature that genuinely makes their life easier or more enjoyable.

Modular smartphones, when done properly, can be part of that too, though even Google has toned down its modular Ara device.

By this time next year I hope we're not looking at yet another set of overpriced, glass-covered black slabs. There's a future in niche—I just hope smartphone makers see it.