>One of the reasons is overlap. Your hands do occasionally hit keys on the other side.
When I switched to a split keyboard I did have this problem at first (with the B and 6 keys in particular on a QWERTY layout) but it took me a week to relearn that. In particular if you use an ortholinear layout on each side there's really no reason to go fishing for keys with the wrong hand.
This in turn means that you can add new keys in the middle that are easy to reach, addressing your 2nd point since it lets you have more "special keys" in the middle.
>Another is key action. You want proper mechanical keys.
That's orthogonal. I like mechanical switches because there's a lot of variety to chose from and they're easy to replace if one goes wrong (a strong advantage on an expensive ergo keyboard that you don't want to replace because of a broken switch) but there are very decent membrane keyboard out there. It's really a matter of taste in the end. After all some people even like those low profile keyboards like the Apple ones that I personally find horrible to type on...
>For me, I also like having a trackpoint. I'm not saying that's common, but a lot of people want /some/ oddball feature like that. For one person, it might be lighted keys. For another, swapped capslock. Etc.
But you're moving the goalpost completely here. It's fine if you like trackpoints but you can't call keyboards "horrible" if they don't support your niche dream build. I don't care for trackpoints personally and it'd probably annoy me to have one on the middle of my keyboard.
>For one person, it might be lighted keys. For another, swapped capslock. Etc.
RGB lighting is fairly standard these days, and swapped capslock is normally easy to achieve either by reconfiguring the keyboard or, if not possible, the OS.
>And then there's the mass of people who don't care about keyboard and buy the cheapest possible model. Split keyboards are $$$.
That is true, ergo keyboards can be very expensive. That being said for the average HNer it's probably still worth it, after all we spend most of our days typing on keyboards, having to shell ~$300 to get a keyboard that will last us for years and improve our comfort is a no-brainer, at least for me.
I've been using an ergodox for years and while it does cost a lot it checks all of your points besides the overlap (which I think is a bad idea) and the trackpoint. It uses QMK under the hood so you can reconfigure it any way you want.
And that's not the only one either, you have the dactyl, the manuform, the moonlander and many others. It's not 2009 anymore, custom keyboards are more accessible than ever (if you have the money for them...)