I think it goes both ways. While many of the AAA blockbuster-type games tend to have the generic "epic orchestral soundtrack" there is a lot of room for unique and original sounds, too. Beyond Good and Evil, Psychonauts, Mass Effect (1 and 2), Jade Empire, Persona 3 and 4 all have pretty unique soundtracks, for example.
That doesn't mean that a more "generic" soundtrack can't work, either. The Knights of the Old Republic games have a distinctively Star Wars-y sound, which actually works in their favor.
Final Fantasy as a series doesn't really count (IMO) as, until 7, they were still using sequenced music (and possibly still even then, I haven't played any of the PSX-era FF games apart from 7, and that music sounded like it was sequenced, even though the PSX could play CD audio). Even then, they still sound unique.
That doesn't mean that a more "generic" soundtrack can't work, either. The Knights of the Old Republic games have a distinctively Star Wars-y sound, which actually works in their favor.
Final Fantasy as a series doesn't really count (IMO) as, until 7, they were still using sequenced music (and possibly still even then, I haven't played any of the PSX-era FF games apart from 7, and that music sounded like it was sequenced, even though the PSX could play CD audio). Even then, they still sound unique.