I think there is something like consistency to the look of a game. A game can be 20 years old and clearly be less detailed in every measurable way compared to a modern title, but still look good. Because there is nothing that makes you think "well they tried here, but it just doesn't look good". Or on the contrary, like when programmable shades were new and fancy, some games had super awesome effects in some spots that looked out of place because they seemed to have been added last minute.

Some games really made the best out of what was possible when they were made, the designers seemed to have gone back and forth until everything came together nicely. These titles are timeless.