I think people are misunderstanding me. Firstly, I said most games. Some games age well, and some games seemingly don't age at all. A game like Half-Life or System Shock 2 ages extremely well. But a majority of games simply don't age well.
Secondly, this is an opinion. If you think Ultima III or whatever has aged well, congrats. I'm not the central authority on what is or is not good. This is my opinion, and my opinion is that most games, new and old, age poorly.
There were over 700 officially licensed games released for the NES. How many of those do you think aged well? I'm pretty damn sure the number is less than 350.