First gen is and always will be my favorite, and because of that, I don't think I'll ever play it will improved graphics. It's just so nostalgic with the cities changing color when you walk through them. I remember when I first got my Red version (I was four :x) I was battling the Rocket guy at the end of the Nugget Bridge (yeah, remember him?), and somehow I lost. The thing is, is when I ended up in Cerulean, I apparently thought that the dude had made me part of Team Rocket because of the color change. So I spent the next few days trying to steal that one guy's Jynx (who wants a Poliwhirl, anyways) until I figured out that I still had to beat the Rocket guy. xD
..of course, this comes from the kid who couldn't figure out how to leave the house at first. I had to have my dad figure it out D;
So, no, I don't think I'd ever play it in full color, although FireRed is a perfectly awesome game in its own right.