Absolutely. And since 3e wasn't tightly templated, as a GM I could never be sure that a new book a player brought to the table wasn't going to destroy the balance of the game. Of course, then you run a Palladium game and balance goes right out the window. 4e does at least have very tight templating and carefully tested abilities that mostly ensure that a new book is going to keep the game at the same power level as all the older ones. They will make mistakes of course (Moment of Glory), but overall I am happy to let new books that I haven't looked over into my game because I trust Wizards' quality control.

As for GURPS, it's a very well designed game, but like Hero System, not one that I cared much for when I first tried it. I've matured somewhat since then, though, so maybe some day I'll give it another try.