IMO comparing Gears or Resistance with Zelda is a bad comparison as the gameplay is so different, maybe comparing Zelda with Oblivion would be a better comparison. I would say the good graphics and game complexity does add a lot to the Oblivion experience.
You don't need to have the best graphics to create the best game, but it can help a lot if implemented well. For instance the Ratchet and Clank titles for the PS2 are good games, but the PS3 game under development looks so much more interesting with twice the level sizes, great graphics, more game complexity, etc.
I liked the original Quake for the PC a lot, but with the later 3DFX glide patch significantly enhancing the graphics on the original, just the improved graphics (the actual gameplay remained the same) did add to the game for me.







