I think they look good on athletic or bodybuilder physiques. But if anyone just likes to wear them, whatever. I just can't get into the OP's notion that someone has to have a specific sort of physique to wear something. I say if someone likes wearing something, then he should wear it, regardless of whether others likes it.
I once showed up to the gym to lift with my friend with my Under Armour compression pants with no shorts over them. My friend said, "Don't talk or lift with me," likely because some folks think men shouldn't walk around in pants that show the silhouette of their junk and buttocks. Well, I didn't give a rat's ass and we lifted together anyway.