I so, so agree! And I think that many of the better GM’s just mow down the rubbish in games. When I run 4e, I let the online chatracter generator do the work of xx+ books and I just make stuff up. The only things I refer to often are the monster books; I can rely on the rules lawyers that you get in every group to keep me relatively close to the rules but I read the fluff for inspiration and ignore the rest. Do I know the page about actions in combat? Tick. Do I need to know anything else? No. I have £150+ worth of books, and I enjoy owning and looking through them but that is not role-playing, that is collecting. What I USE in my weekly games would fit in a six page pamphlet. The Keep on the Shadowfell, Thunderspire and all of Nentir Vale that I ran a game in for nearly a year, existed nowhere except in my head (and is still not written down anywhere). My Saturday Pathfinder games also have nothing written down. I will use maps from books and the names of NPCs but their stats and personalities, their stories and motivations, I just make up.
When I GM, I try to obey only one rule: GO FOR IT! If a player comes up with an idea that sounds cool, it is likely to work. If the clue is in the desk in the library but they don’t look there, then the clue will be where they DO look. I am not going to derail a story because players do something that I didn’t expect or don’t do something that seemed obvious to me when I thought of it. I try to run stories like action movies; the hero doesn’t die in the first reel, the villain will work from behind the scenes but in the end will get his just desserts from the heroes, wounds are bloody during the scene but quickly shaken off and some bit-part actor never outshines the hero. Yep, even my fantasy games should feel more like Die Hard than On Golden Pond!
A GM should decide what kind of movie his game is going to be (action or slow paced, a rom-com or, heaven help us, a documentary!) and if it wouldn’t happen in a movie of your chosen type, it shouldn’t happen in your games.
That’s my two pennies worth.