The general rule is that good games sell systems ... People do want good graphics in their games but the quality of graphics of a game is typically judged in relation to other games on the same platform; most people will not compare the graphics of a game on the Wii to the PS3.
Now, the risk associated with the PS3 is that games are more expensive to produce, and have longer development times which means unless they have more publishers working on their platform (and they have more users to buy games) they're going to have less games available; at the same time it is selling poorly and has a massive price tag that keeps consumers away, which means publishers should be reconsidering how much support the PS3 really should get.
Videogames are one of those self justifying cycles in that people buy a platform because they think it will have the best games, developers focus on that platform because it has sold the most units, and the system has more good games than its competition ...
Essay Pro