Pac-Man and Tetris don't rely on gfx or sound. They do well without 'em. An RPG however is a game that should pull the player into another world. When this world sucks because the gfx are lame, the music is crap, the story is bull and the characters are flawed, then the game quality is low.
The more the game resembles another world or a story, the better the art (gfx/music/sound/story) needs to be.
The more the game resembles another world or a story, the better the art (gfx/music/sound/story) needs to be.