Agreed, Jim! Realistic games might be impressive during their current generation, but 10 years after, they will look like garbage. I remember seeing Def Jam on my friend's PS2 many years ago and saying "Holy shit, this looks amazing! It's so REAL!", nowadays? It's incredibly meh...
However, when I look today at Sonic 2, it still looks amazing. And no, it's not nostalgia, I really find this game to be ageless. If I play it today, 15 years after I first played it(I believe...), I still enjoy its graphics.
Unfortunatelly, I can't say the same about some other incredible games, like FF VII for instance(death threats in 3,2,1...). Don't get me wrong, FF VII is and AMAZING game, it really is and I have enjoyed it a lot! But to be honest, I find it REALLY hard to overlook the graphics today. =/ And believe me, I'm one of those guys who say "graphics aren't really important, gameplay is what it's about", and I stand by that! I really enjoy games like VVVVVV or Minecraft, but the question is that those games followed a specific ART STYLE which will not look dated eventually, whereas FF VII strived for something a little more realistic and "mechanical".
I guess the keywords here are "art style". Games that pick a style and don't worry too much about being realistic usually age better, while games that try to emulate the real world will eventually look dated. That occurs mainly because the hardware available during their generation has a limited computational capacity which will be considered ridiculous when the next generation comes around, just take a look at Moore's Law, it will make sense.