They were one of the best bands in an era where the competition was lethal but they didn't really become successful while at the same time not sounding "underground"/atypical enough of the era to become cult beyond psychedelia/late 60's (as opposed to, say, Velvet Underground, Stooges, even Mothers of Invention to a certain extent). They had a sound that was simultaneously distinct *and* typical of the time but since they never really "made it", they will never become more than a cult-favourite for people specifically into american late 60's west-coast rock...