NEM was a box office flop now that alone perhaps wouldn't be a reason not to do another film but I think with ENT tanking in the ratings as well they simply felt the market wasn't there.
I suspect this was the real nail in the coffin.
Nemesis alone failing at the box office wasn't enough to kill the prospect of another movie. But
Enterprise failing on TV screens as well just meant that the bottom fell completely out from under the Star Trek franchise. It gave various people in various stages of importance pause for thought.
See, this is where I respectfully disagree. Not about the various tv/movie producers/executives being scared, but the reasons why they were.
IMO, those same execs. saw "Star Trek" as a brand name and anything they slapped on it meant cash and that's exactly what they did with it, slap it on anything. So seeing the crap that was being made at the time had Star Trek on it and wasn't bringing in the money then it must be "franchise fatigue" and not terrible quality product. Forget about the fact that Star Trek, the original, was still doing just fine in reruns. That doesn't track their radar because reruns don't mean big profits. So my point is this: people weren't sick of Star Trek, they were sick of crap that had the Star Trek name on it and weren't going to take a gamble on yet another crap product with the
brand slapped on it. It was all crap to them (executives), they didn't understand or care why people liked it, why we are
still discussing shows that have been over decades later, so one more piece of crap should make just as much as another as long as it's got that brand.
So I think a Fifth movie would have had a real chore ahead of it but could have been great if it had the chance. A good movie might not have had the opening weekend they wanted but it would have had good word of mouth and legs for a longer showing time. Unlike the last two movies. And I'm sorry Enterprise fans but that was not a good show.
I think if they picked up with Patrick Stewart as the star and kept some of the others, like Levar Burton and Michael Dorn, it could have been a good movie, what ever it would have been. Maybe Worf could have been the first officer of the E E under Picard and Geordi the 3rd in command, it would have been nice if they had a first contact with a strange new civilization and showed how they try to get past their differences to reach some kind of communication with each other, possible even after some earlier hostilities. I think even if one of the other cast was brought back and the earlier hostilities actually resulted in their death/injury that it would make the accomplishment of the communication that much more of a victory. Maybe have the doctor or go. Not because I don't like her but because I do. Space is not for the timid. It's easy to kill off throwaway characters or characters on a show that's cancelled and it has little to no dramatic weight to it. Just imagine how powerful it would be for Picard to negotiate a peace with a new civilization that had killed Dr. Crusher through a misunderstanding. And for all of the TNG fans that feel like the ensemble was already getting cheated and this is even worse, I'm sorry but the only one that really would have the acting ability to do this would be Patrick Stewart. It would have to center on him. I personally think he could still be in a movie as Picard today, he's more than proven himself, but then I'm not an executive.
If a Star Trek movie even gets mentioned *at all*, and that's a very big If, then it's usually TWOK that gets the gong. First Contact is most certainly not the critics and fan's favourite. 
100 sci-fi movies? There probably aren't that many more than 100 major scifi- films.... Oh God... you like The Motion PIcture? 2nd or 3rd worst trek film. 
