Why this show failed
I watched Enterprise when it first aired, and I'm recently watching it again on Netflix. I actually enjoy the show, as I enjoy all things Trek, but I can see why the show was cancelled so soon. Here are the reasons the show didn't work (according to me):
1) The look of the show
When I first heard about Enterprise, I was really excited. Since it was supposed to take place before TOS, I was looking forward to seeing some really interesting, retro set design in line with what would have evolved toward that of TOS in terms of colors, technology, uniforms, etc. Instead we got a slightly evolved version of modern space shuttle or submarine decor. I know they were going for the "realistic" look, but I would have rather seen something more along the lines of the set design of the JJ Abram's movies, although even that looked way too advanced compared to TOS.
2) Uninteresting characters
Whoever did the casting for this show did a terrible job. The only character that stood out to me was T'Pol. Everybody else was invisible. I did also like Trip, although I found his nice southern country boy persona without any interesting backstory a bit boring. Paris from Voyager was a similar character, but he at least had an interesting backstory.
3) Captain Archer
I love Scott Bakula. But I don't think he is Star Trek captain material. Star Trek captains are supposed to be strong and principled (Picard, Sisko, Janeway) with perhaps a little mischievousness (Shatner). But Bakula always seems to play the serious but befuddled Everyman who always looks a bit in over his head. When the show started he was principled in that he eschewed violence and torture. But as the show went on he was torturing everyone in sight. I know the producers probably wanted to show how his character evolved in response to the challenges he encountered, but it just didn't seem to work.
4) The Aliens
This show was supposed to take place to over a century before TOS and a few decades after first contact. I'll accept having a Vulcan aboard on this first mission, but some strange alien doctor in charge of the crew's well-being? I would have preferred a human doctor, perhaps, like Bones in TOS, especially if he exhibited some friction with the captain.
5) Story Arcs
Those long story arcs just didn't work. Star Trek works when it's episodic--something new each week. It gets boring when a single story line dominates.
6) The song
The first time I heard the song, I hated it. It just didn't fit Star Trek. I admit, however, that I actually like the song now. But I think they should have stuck with the tried and true classical music/monologue opening.