Oh yeah, there are a ton of these classics that could be amazing with today's hardware. I figure most are not redone because, at this point, just who owns those titles is not easily found out.

I know this is a problem that Piko Interactive faces - they purchase the rights to classic games, and in many cases finish them up, and re-release them (as well as port many to new platforms). I can only imagine what they pay in lawyer fees to find correct owners of the titles they do release.