In general I think that the ST movies are usually rather average or downright bad. Many episodes from the various series are vastly superior.
The good movies:
1. First Contact (great entertainment, but some sloppy writing prevent it from being truly great)
2. Wrath of Khan (works as Star Trek, works as a separate movie)
3. The Voyage Home (good comedy)
The average movies:
4. Insurrection (good idea, but too flawed)
5. The Undiscovered Country (not a good movie IMO, the sloppy writing ruins it)
6. Nemesis (tried to hard to be the new Khan, but some nice action and essentially the same movie as the lame reboot)
7. Generations (interesting to see the tv series step directly to the big screen but the nexus doesn't make any sense and why make Kirk only interact with Picard. Wasted)
8. The Final Frontier (I don't get the hate, at least it's somewhat funny)
9. The Search For Spock (too boring)
The bad movie:
10. The Motion Picture (pretentious crap)
I agree that many episodes are far superior to the movies (Best of Both Worlds for example), since Star Trek's prime has been and shall always be on television. However, I disagree with some of your critiques (but I do respect your opinion).
The Undiscovered Country should be listed with the good movies. It really showed the prejudice that Kirk had towards the Klingons, showing that his son's death really did have an impact on him. The movie was a mirror for the cold war (which was ending at the time of this movie). Showing the harshness of the Klingon prisons, and their unfair trials, we saw a lot of corruption in their government.
The Motion Picture is rather slow and boring, though it reminds me of 2001: A Space Odyssey. It has the feeling of what it would feel like to be in outer space. It was the only Star Trek film that showed what it really felt like to exist in the future (or the future in the Star Trek universe anyway). It was a pure Sci-Fi film, and it had a great twist at the end if you were willing to watch it. It had a beautiful score, and introduced many elements that we grew to love in the ST franchise (the new look of Klingons, the theme music, the warp core engine design, etc). This at the very least should be average, not "bad," especially since you list "the Final Frontier," "Insurrection," and "Nemesis" as average.
Search For Spock is a bit boring, but only when viewed as an individual film. It is a nice bridge between "Wrath of Khan" and the "Voyage Home." It had a lot of fun moments, such as both the stealing and the destruction of the Enterprise. I view ST II - ST IV as a trilogy within a larger film series.
Star Trek (the reboot) was done brilliantly. While it is still a reboot, it has a connection to the original timeline, where Prime Spock and Nero originate. Many Trekkies will hate it, others will accept it. It has the ability of creating a whole new Star Trek fan base while pleasing at least a decent amount of Trekkies.
Here is my list of the movies:
Great movies:
Wrath of Khan
Voyage Home
Undiscovered Country
First Contact
Star Trek (2009)
Good movies:
The Motion Picture
Search For Spock
Average movies:
Generations
Nemesis
Bad movies:
The Final Frontier
Insurrection
