Magnitus: I agree, but at the same time, the rulebooks and supplements are supposed to provide a framework and inspiration for role-playing which you can tweak or expand on.
That is true of the second edition (reading the books would give me a lot of inspiration for campaign material).
In comparison, the little I read from later editions seemed quite sterile.
Bonobo_Power: I never encountered this problem, actually, on the contrary, I was overwhelmed by the amount of stuff added by the tons of rulebooks of 3.5 (can't really speak for 4ed because I never played it and only read some stuff from the PHB). For me, the real problem is that with so much stuff, is nearly impossible to keep everything balanced and players can easily break the game abusing the rules... one of my "friends" actually tried to do that (and later on even downright cheated -.-" )
What I recall in regard to variety is that they have over 5000 prestige classes.
Each supplement they make, they add some prestige classes.
Each is heavily described in terms of play mechanics.
In the end, they kinda feel like they are all the same (maybe 5% of the described prestige classes are cool, the rest kinda suck I have to say).
In the second edition, they made a lot of kits for the various classes, but because each was approached from a role-playing perspective first, they felt more flavorful (for each kit, the role-playing section was big and the mechanics section was smaller so you could kinda tell that they first came out with a lot of role-playing rationalization for the kit before throwing in play mechanics).
Speaking from a game-making perspective, I believe that's the place where you want to be. You want to rationalize the various pieces of the game in terms of flavor BEFORE you translate them into play mechanics.
The best analogy I can come up with in terms of DMing is a friend of mine who felt compelled to create his entire world before we even started the first game.
He could tell you all sorts of things about that city or that royal family he created, but when we started playing, it all felt quite bland and without much flavor.
Made me wish he had started focusing on a certain area and put a lot of twists and turns into it (which has always been my approach... create the world one bloc at a time and it will be all the richer for it, because you put a lot of thought into each bloc).