Arent most bands that have a somewhat original sound and flavor?
That's true. A lot of bands develop a great sound and then spend the rest of the careers building and not turning it over. What a lot of critics view as "progression" is really the work of producers giving the product a new paintjob. And, sometimes, when somebody throws in a dubstep mix or hip hop cameo, they are not progressing, but diluting their sound. (Though I think what Muse did with Madness is just marvelous. It stands on its own as a love song.)