Absolutely not. If you want an epic feel to a game, you need an epic score. I don't know about FPS games, but most RPGs need that (although a good score is not a substitute for making a substantial game.)
That said, greater variety and contrasts can add to the character of different locations and points in the game. Morrowind was stirring, and it was fantastic when the score hit its emotional highpoint when you were crossing the peak of a mountain or rounding the corner to see a whole new area laid out before you, less so when you were fiddling in your inventory. And it was repetitive.
With so many RPGs set in a Tolkienesque fantasy world, it's inevitable that soundtracks will try to imitate the Lord of the Rings. Vampire The Masquerade: Bloodlines was refreshing and fun, because the setting was refreshing and the soundtrack had room to be different. More RPGs in more original and interesting settings, please, with music to match.
(And FPS, if we must.)