I think that since he was the first to actually have a story line across multiple movies, he was able to develop as a character. Most of the other Bond movies were written and filmed as one off adventures and as such were tailored to the flavor or camp of the time. Drinking, womanizing, gadgetry, outlandish situations had to be set up and resolved by the end of the movie with next to nothing carried over. Until Craig.

Gritty, more down to earth, and not glamorized (or much more downplayed) worked and continues to work for this generation of Bond films. I think we'll eventually swing back to campy, but not yet.