The reason why PS3 was using graphics as a selling point is because of their extremely shitty lineup of games upon release. Xbox 360 had been out for about a year and had some good games already out and upcoming, while PS3 was releasing nothing that was noteworthy. So when your lineup sucks, you need a new marketing plan... so they decided to go with "Our graphics are leet, lookit our Blue Ray!" which still didn't really sell ppl all that much... I got the 360 because of the games. I mean isn't that the point of having a console? Playing games? Why buy a GAMING system that is devoid of actually decent games?
Anyway, the PS3 decided to market as an entertainment system due to blue ray and great graphics capabilites, instead of as a good gaming platform. But then again, PC will do that too with more Hard Drive space and more programs. Not to mention the way you can easily pirate your media on PC. Ultimately, the only reason PS3 did so great, In my opinion, is Hype, Brand (Sony), and poor hardware on the Xbox's part. Oh, and Sony underselling the PS3's Blue Ray drive and actually LOSING money on it. But Sony's a big boy, they were able to take it.
I would also like to point out that one of the currently popular PS3 games, Little Big Planet, doesn't have amazing graphics. So no, Graphics are meaningless and not really a selling point.