Lost and Threshold had those horrible sound effects instead of theme songs.
What they did for Lost
was appropriate. It went well with the show's eerie ominous tone. If they did do a full theme & credits sequence, something like what they're doing with The Walking Dead
might have worked.
Enterprise is so far the only TV theme I have muted.
I liked that they did something different. To me, it was preferable to yet another orchestral piece.