We really abandoned the idea when computers got so cheap that you could just have a separate computer at each station. Mini PCs are $200, how will your solution compete with that? Thin clients won't get much cheaper than that as they have all the same hardware. Thin-client-less multi-user systems might, but the extra administration complexity ($howmany per sysadmin hour?) will make it a tight squeeze and you may as well just stick with what's familiar.
You could have more luck with AIO PCs.
Everything you say is true, NUC's kind of ate this problem.
Still, one of these days I'll get around to setting up a system like this, just for the fun of it.
I can think of a few applications where it would be fun. Music-making, for example ..