I have to respectfully disagree with you on that. I would personally be put off playing an older game since low-res, pixelated graphics annoy me, but I know enough not to base my decision on that since lots of people love playing games from their younger days. However, games like C&C & WC2 are nearly twenty years old (holy crap how did THAT happen?!) This means that not only are there game players today who weren't playing games when WC2 was released, there are people who weren't even born when these games were already retro classics :) If those game aren't being marketed and sold anymore, people have to go out of their way to find they exist and then find an old copy floating around, and get it to run somehow.
I actually think something like WC2 re-released with token polish as a cheap RTS could sell. Not topping any lists, but of course we're not trying to be a best-seller - a few thousand sales is wonderful.
Anyway, that's my opinion, I'm happy to agree to disagree. I don't plan to make a total clone, my motivation is to make an RTS which I want to play, but my thoughts are more incremental than massive genre redefinitions. Well - I have much bigger plans for a half-dozen RTS games, but making a "bog standard one" would seem a better bet first.