The danger of writing prequels in science fiction and fantasy is that fans of these genres often display an almost irrational desire for perfect consistency throughout the lifetime of a franchise. The desire for canonical consistency in the Star Trek franchises is a clear expression of this, with some fans insisting that their own internal representation of the series mythos is somehow factual. In this light, attempting a prequel series was always going to be difficult. Perhaps this contributed to Enterprise's eventual cancellation.
On the other hand, perhaps it was just that the theme tune verged upon musical abomination. It certainly helped me stop watching!