I think its sad that the biggest pride people have is sales, at least graphics and power add something to the gaming experience, what do sales add? nothing much if any.
Sales definitely doesn't mean whether or not a game is good, however I think the people you're referring to are mostly exclusive to this site. The graphics and power people are much more common. However, in regards to your comment about sales, for some people they believe that as a result of a game being good, it should have higher sales rather than high sales being something itself that makes the game better.
Sales is much more to do with business in the realistic sense, and I would say higher sales give a game a better chance to gain more exposure and have more games like it come out (not rehashing). /redundant rant over.