Some part of that is that a lot of the mech keyboards are DIY projects, and smaller keyboards are cheaper and simpler to put together.

I personally am a split ergonomic keyboard enjoyer. I use a Keebio Iris at work and a Unikeyboard Diverge TM2 at home, which are a 50% and 40% respectively, both split.

The thing that I like the most about small form factor keebs is that compared to a full keeb, I don't have to move my hands so much to do basic and oft-repeated tasks. I don't think about it as removing keys as much as bringing them closer to my fingers. For example, on a 40% keeb, all keys are within 1u away from your fingers' home position.

I am totally in love with programmable layers. I programmed both of my keebs similarly. Examples:

• The key to the left from the A key, usually the Caps Lock key, is a dual-role key on my keebs. When you press it, it acts as Esc, and when you hold it, it acts as Ctrl.
• I have a key on the left half that makes my right half into a number pad. Just like that, I completely eliminate the need for a physical one, and I don't even have to move my hand to use it.
• Switching tabs (Ctrl + Tab, Ctrl + Shift + Tab) is a very often used pair of shortcuts for me, and they're relatively uncomfortable to press on a full keyboard. I moved them to a much more comfortable position - I hold a key with my thumb and switch tabs with two of my other fingers without having to move any fingers from their home position.
• I use virtual desktops in Windows quite a lot for working in different contexts and I mapped switching desktops (Ctrl + Win + arrow keys) to a similarly accessible/comfortable position, same with some others like Alt + F4.
• I am a software developer and function keys (F1-F12) are quite frequently used in IDEs, especially in combination with modifiers (Ctrl, Shift, Alt). With a full keeb you often need to move both of your hands quite far from the home positions to press those combinations. With a small keeb, I use one of my hands to press the modifiers (which I mapped to the home row in most of my layers) and a finger from the other hand moves just 1u up from the home row.

Of course it takes a bit of trial and error, changing the way you think about how the keyboard works, and retraining your muscle memory, but as a person who spends 8+ days working with computers, I think it's ultimately worth the investment of time, money and effort to make my weapon of choice as ergonomic and comfortable to use as possible.

For when I can't sit at my desk and use an ergonomic keeb, I also made myself an AutoHotkey script that makes the CapsLock of a regular keyboard more useful. It would be for another writeup, but as an example, it makes it act as Esc when you press it and when you hold it, it activates an extra layer -- as an example, it turns the keys HJKL into arrow keys (left, down, up, right) and the keys YUIO into Home, PgDn, PgUp and End, and turns the numeric keys into function keys. I can still work with a full-sized keyboard, but whenever I am forced to, I am reminded how clunky it is and I long for my keeb or at least my AHK script.

In summary, small keebs are cheaper and easier to make, and they bring all the keys closer to your fingertips, making it more efficient and comfortable than full keebs, with the small cost of retraining your muscle memory.

I have a 60%, an 87 key, and a full keyboard, and play a fair amount of games, while also doing productive work. The full one is my favorite, and the 87 is close, add I rarely just the numpad, but it's really nice to have when I do.

There's some utility in a smaller keyboard, but I'd rather have the function keys than one row less. I barely use the 60% except as my spare keyboard when I need one that isn't attached to a machine.

Gamers seem to drive the market of people who don't buy the cheapest or most practical computer accessories, look at RGB lighting in cases. Nice, big mechanical keyboards are hard to find, but not impossible.

I use a mini keyboard for both gaming and work.

For me, the main draw is the size - a smaller keyboard allows you to have your arms in a more ergonomic position (ie, shoulder width apart). For someone who works on a PC all day, ergonomics and posture is imports to me - especially now that I'm older and have suffered from carpal tunnel in the past.

I've been using 60-75% keyboard for about a decade now and don't miss big keyboards at all, neither for gaming, nor for work.

AMA.

You can just get a usb number pad for a few bucks.