Star Trek should be a higher and be a great example of people unwilling to move on to another show with different characters, I mean look at how many people were less willing to see TNG when it was first announced because it didn't have Kirk and Spock in it!
^This.
I think the problem might have a bit to do with not having someone viewed as THE Star Trek person - the one that holds the vision of what ST is and should/will be. I had started a tread about who the future standard-bearer could be (not to promote the tread, just reference). There doesn't seem to be that person(s).
Without the vision of the original creator (Roddenberry) or someone that had been with the show in the past and was linked to the creator in some manner, there doesn't seem to be anyone with the credibility and therefore a strong enough voice to push such an initiative through. I don't think Berman and Braga, although previously connected with the show and the creator, would be very popular. Of course Frakes is a fan favorite, but he was unable to convince the folks at CBS.
Not that I'm trying to make Gene Roddenberry out to be some demi-god, but it was his and he did have the vision and the ability to convince people to televise it - even before syndication was popular (thinking of TNG here).
Not that I disagree with you there, but the original creator of a show, or a tangential connection to said creator, isn't always necessary for a spin off of the original concept to be successful.
For example, take Stargate. In my opinion, SG1, Atlantis, and SGU far exceeds the original movie by Roland Emmerich, and with Emmerich finally "reclaiming" Stargate and doing a reboot, I think he will actually be seen by most fans of the series as a pretender to the throne of sorts, of his own concept.