Yeah! Before 3D!
I know that 3D games do have there fun points, and one could possibly (on a long shot) consider them "revolutionary," but they're just not the same. No 3D platform game can hold the same fun and challange as the 2D type (all the "golden age" games.)
With a true game you run through it, finish all the levels, get a "perfect" or such, and think "Wow! That was a fun game! I can't wait to go through it again!"
With most 3D platforms, however, it's more like "Wow. That was fun... I wonder when the sequel's coming out?"
Think about it: if game developers were to move away from the whole "3D is better" mindset just for a moment, they would be able to see what else could be done. Instead of investing time and proccessing power on fancy textures and millions of polygons, new games could be 2-dimensional (in classic style, maybe enhanced to a limit) with maybe some nice effects. But much bigger.
I'm sure I can find many gamers who think that many of these new games just didn't last very long. Not only the actual run-through, but especially in replay value. If the space used for the 3D world was instead used to make more of a 2D style game, it could be huge!
That's all I have to say right now, but take your favorite classic game, make it much longer, and think about it...