Depend on the game, graphics can enhance gameplay if used correctly, such as collision detection, details, etc, to give a better sense of space/dimension and ease of identification. But, only a certain level of graphic is necessary for a game, any more than that may detract from the game (not as in too much graphic detract time play, but as in more time spent on graphic may mean less time spent on developing other aspects of game) Example of this includes most 2D Platformers, while I am not saying the 3D is bad, but there have not yet (keep in mind I haven't played too many 3D platformers) been a 3D platformer game (with analog or digital) that quite recreate the high precision of the 2D platformers (depend on game, it's not like there's no bad 2D platformers)
In addition, there's something called "Imagination" that we used to make a whole picture or imagine more details way back when such detail wasn't available, so as long as a game have reached the necessary graphic capacity to flash out the gameplay, it would age well.
Finally, gamer tend to go with whatever the graphic they were first introduced to play, and it's more of what they are used to and how much they can accept new/retro/different things in order to play game with different graphic capacities.
P.S. Nostalgia also plays a factor when comparing games, although often enough that a game is still great without the nostalgia so it's definitely not the only factor.
P.P.S. On a side note, human perception feel change in roughly 1/60 or so for visual sensation, and 3D graphics require exponential increase to achieve that different. In short, Graphic increase will need to become exponentially high to make someone go WOW. yet hardware doesn't increase at an exponential rate (it increase by multiplicity as per Moore's Law). I'll leave you, the reader of this comment to fill in the blank.
I am a PC gamer, and also have a NDS now, but without access to a Nintendo Wii until End of 2007.
Currently playing: Super Smash Brothers Brawl(Wii), Mystery Dungeon: Shiren the Wanderer(DS), Dragon Quest Heroes: Rocket Slime (DS), WiiFit(Wii)
Games Recently Beaten: Final Fantasy Crystal Chronicles: My Life as a King (Normal; Very Hard after the next DLCs become available)
1 word: RTFA