Well said, epicac! Seriously, one has to wonder whether or not most people who buy a lot of games actually PLAY THEM. A handful of good/great games can go very, very long way, if you take your time and savor them, and ESPECIALLY if you have a lifestyle that is well-rounded enough that you aren't merely playing videogames constantly. I don't mean to sound rude by saying that, but just to make a point--of course, I don't think it's the case that most game-buyers (who aren't necessarly gamers) simply beat their games too quickly, although I guess there is a case to be made about the simplification of modern games.
I've often used the argument, "Yeah, XBOX, which is a decent enough system, to be fair, has more games than GameCube. So what?" The fact is, my belief is that the GCN has a good-game to bad-game ratio that's definitely more good than the XBOX. In fact, of the exclusives on XBOX, I can only think of two or three games that are out that I truly MUST play: Halo, Panzer Dragoon Orta (what Saturn owner could turn this down?), and the Shenmue II remake--even though I have the DC UK import. Couple that with Shenmue III and a few others, and the XBOX would certainly keep me busy for a while. However, the first and second party Nintendo titles ALONE (and there are many 7/10 and 8/10 games from third parties that warrant a buy very much) are more than enough to a) bring much fun into your home for a very long time and b) prove quantifiably that Nintendo is working harder than ever before.
Your comments about gamers who only buy the 9's and 10's were very apt. First off, a lot scores are just badly rationed out, and very often (as at IGN, for instance) do not gel at all with the written review. I dream of the day when everyone reads every word of reviews, skips the scores, and the scoring system dies out for good. It never will, I guess, but it never hurts to dream. A lot of those 7's and 8's are true gems. Heck, I can't say how many different critics have given some of my favorite Treasure games "mediocre" 6's and 7's. If I went by the reviews sometimes, I'd miss out on something truly great.