You're absolutely right. However, as I said in a prior post, if written and directed well, I believe these films would be successful. I will also state that I believe they would be considered among the best science fiction films made in the past twenty years or so.
Because of your personal investment in the Trek universe, I don't think you realize how little people care about it and how detrimental it could be to the commercial and critical success of a movie. People would not be excited about a story starring Picard, Ezri and some character from Enterprise: they would think it's laughable.