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 ..
I like this guy's series on building out a collection of SunRay thin clients connecting back to his SPARC server.
Linus Tech Tips did one for gaming, just for fun. https://youtube.com/watch?v=uKJw8IKVYQ8