I think I understand what you're saying. But IMHO, the fundamental problem of Sybok being the one who makes things happen is that the audience really has no vested interest in what Sybok wants. He's just a plot device to make Kirk look like he's the "last man standing" while everyone else (even Spock!) has buckled under this religious fanatic's brainwashing.
I think it would have worked far better if both the Romulan and Klingon governments had sent official expeditions (instead of Klaa's ship just hanging around doing nothing and going to Nimbus III just to fuck with Kirk) and that the Planet of Galactic Peace was a far more important place than it was depicted in the film.
Unfortunately, as I mentioned to CorporalCaptain above, Sybok was just a plot device and ergo, all of his backstory was just exposition for the "meeting with God" thing.
The ironic thing is that if Sybok was a character in DSC and was developed over time just like you describe, I think he'd work out great
Again, I felt that the "Great Barrier" was just a plot device (and not a very good one, since for all the bitching they do about not being able to cross it, they cross it just fine.) Now if it was the
Galactic Barrier then at least we'd have some context about how dangerous it is. It makes people turn into Gods, you know...
The crew each facing their personal demons was definitely a good concept.
Again, good concepts. Not so much for a two-hour movie though, but definitely for a series.
...would be the one thing I'd get rid of. Sybok being a logic-rejecting Vulcan with special powers is inherently interesting in itself without the added saddle of being Spock's totally-unknown-before-now brother or that they'd need to have had any prior knowledge of each other.
As I said before, having the Romulan, Klingon, and Federation governments actually take the incident seriously and that Nimbus III was actually an important place as opposed to "we really don't give a crap about this place or the people we sent there, and we care about it so little that the only people we're sending are a bunch of geriatrics on a ship that's literally falling apart" would have been a better use of dramatic tension.
These go hand-in-hand. Because they are what makes this film so bad. The audience already knows that Sybok isn't really going to find God, and whatever planet Sha-Ka-Ree is or where it's located, it will not be heaven. So virtually ANYTHING we see is going to be a letdown. Did you really care about the alien or its motivations other than "it's trapped and wants to be set free to do more mischief?" I sure didn't. So instead of having a ham-fisted idea of "searching for God," perhaps it would have been better if Sybok's motivations were instead focused on something more realistic, like trying to forge peace between the Romulans, Klingons and the Federation by using his powers to break down the barriers between the three powers, and having the three representatives return to their respective governments with Sybok's message.