Come on! They are not MARRIED to a particular style, however dearly you would wish them to be just that.
Writers, filmmakers, painters, musicians - anyone with an artistic vein can not be expected to stick to one specific thing. People change, so things change, not the other way around, although I agree that especially Americans seem to be highly susceptible to fads of whatever kind the corporate-owned media feed them. Then again, the whole American way of doing business, of SELLING things has taken hold globally and so, people not much given to use their own mind miss out on a lot of culture in general. Sadly, that is the majority of people.
As for me personally, I hated the change that many a band went through in terms of style (and stopped buying their albums). But I always remind myself of one thing: if you do not enjoy the thing you're creating (be it a book, a drawing, a film, a song), you end up being miserable.
And now I order Warrel Dane to get rid of that ridiculous goatee and reform Sanctuary.
) On the other hand I love Motörhead and Running Wild for staying themselves pretty much all the way through. I like the changes of Rush and of Savatage, I didn't like the changes in Metallica and Slayer that much. Changes and developement can be fantastic, and it can happen not to please us. In the latter case, well, just drop the band, don't buy their records anymore. Period. Betrayal? Nah... they shall do whatever they want. They owe you and me nothing. It's their music, it's their life and it's their bandname... They may use it as they deem appropriate. People shouldn't take themselves and their opinions so seriously.