Yes, yes, they do. My change came after a few years of 1e, wanted something darker and grittier, so went to Warhammer. With 3.5, I found that system worked well with my home brew campaign.
I'm just all over the place.
Heh, interesting.
I don't think "of course they change" is reall all that true. The Shaman, for example, has stated that while he might try this or that game, his tastes have remained fairly stable.
I think I'm on the other end of the spectrum here. Every campaign is different from the last one. Different in style, focus, theme and actual play.