One of the things that makes me cringe when I read various gamer-related message boards and blogs is the terms "crunch" and "fluff". Language and psychology go hand-in-hand, and I think the pervasiveness of the terms heralds a shift in attitudes towards gaming over the last couple of years.
Back in the day, rules were called "rules". Background was called "background" (or, alternatively, "setting"). Early on, the approach to both was an extremely light touch; the original World of Greyhawk folio, for example, is almost Hemmingway-esque in its brevity; you had just enough information to get started. The same thing goes for the OD&D rules (and, I would say, the first three of the AD&D rulebooks).
You could say that trend ended with third-party products like Harn, which was incredibly detailed in presenting its setting, or Arms Law, which was a very detailed combat simulator (and which eventually grew into the Rolemaster game system).
But now it seems that the balance has shifted away from setting and background, and over to rules. By way of evidence, I submit the rise of the terms "crunch" and "fluff" to describe rules and setting, respectively. I think the terms themselves betray the bias of their users.
"Crunch" is hard. It's solid. It's necessary. It's the sound of your boots on the gravel as your character stomps along like a twenty-sider-fueled killing machine hurling fireballs and lopping off the heads of demon lords with your +5 vorpal holy avenger frostbrand two-handed sword. It is the key to value.
"Fluff" is ephemeral. It's light, easily transferrable, and brings little heft per dollar. It's vaporous and vaccuous, and can be blown away by a small gust of wind caused by the backswing of a +5 vorpal holy avenger frostbrand two-handed sword taking off the head of yet another demon lord. It is of little value.
Now, these are not universal attitudes, of course, and I am not trying to say that they apply 100% of the time. But they are reflective of the overall attitudes, and the respective values placed on rules vs. setting. Just look at the newly released Forgotten Realms book. WotC made a deliberate calculation that they wanted to make the Realms more accessible. How to do that? By wiping out all the accumulated background ("Realmslore" as fans of the setting call it) so new gamers wouldn't be overwhelmed. After all, it's only "fluff", right? It can't have much value.
Or, look at Pathfinder. Are folks really jazzed at the default gaming setting that the Paizo folks are coming up with? Or is it the rules-- an updated version of 3E-- that is generating all the excitement? Setting is almost a necessary evil that you need because adventure paths have to exist someplace. It's just "fluff".
Perhaps my aversion to the denigration of setting is a function of my style of play. I DM a sandbox game; no adventure paths, no overarching plot driving the characters in my campaign. The world is there, humming along, and the players are free to roam about that sandbox any way they choose. In order to run a game like that, you need a lot of background, as the characters' interactions with that background drive the action of the campaign. And you can't do that with just fluff.