Because when you sit half an arm's length from your screen, you can't use anything much lager than 22-24". Even a 27" would be unwieldy causing you to literally take a step back to see everything without having to physically turn your head.
Me personally, I prefer to sit across the room, console-gaming style. A monitor the size of a TV better suits my needs.
I have a few 27" Overlord monitors & a few old relic DELL 27" 'ers that are too small. (coincidentally, I enjoy :10, better than :9)
My keyboard trays are swing-out, mechanical swivel boards.. and One can easily be 40" ~ 50" from the monitor if sitting back in chair.
The distance I sit from a 32" is not an issue. I don't live in an apartment and know exactly the size I need. I am just having difficulty finding the specs/performance I require.
Don't forget, some people have 75" TV's and sit 8' away. (I am talking 32" @ ~4')
And I am not alone.
Been doing reading on other forums and there is a massive huge gap in the PC gaming world. If people will play Consoles on 60" LED TV... why not PCG's on 32" Monitors..?