I don't think the Enterprise actors were any worse than the actors in the other series. I was really excited and looking forward to the show when I first heard Scott Bakula was going to be the captain. He's always been one of my favorites.
Totally agree the music sucked. I still remember my visceral reaction to that bubble-gum rock ballad piece of crap song the first night. I think I made a very vocal post about it on this forum. I'll have to look it up just for fun. In my estimation Enterprise would have been 25% better just by having NO theme song at all. Just a black screen with the word Enterprise leading into the start of each episode would have been better then that crap mtv whiney video thing.
Did I mention I hate the theme song?
If the theme song put Ent on bad footing, what pushed it down the stairs was that god-aweful story arc about the Xindi and that damnable temporal cold war. It's not like they didn't have ready made powerful advesaries in the Romulans and Klingons, they had to manufacture some lame arsed race that wiped out Florida, but somehow never got mentioned in any of the series or the fourteen movies that supposedly happened after that. Maybe it was such a traumatic experience for humans that we blocked out all memory of it as a species?
Turning the middle two seasons into Star Trek: Quontum Leap killed the series for me. The first season wasn't aweful, especially by Star Trek standards. The last season actually was decent. It seemed like they had finally run out of grand ideas how to kill the show and decided, "Hey, maybe we should be doing a show about Star Trek here?" But by then it was too late. It was dead, Jim.