I do agree with the contrivances, and there's also a clashing of ideas. When Kirk steals the Enterprise and outruns the Excelsior, it's done in such a triumphant way that it's as if Kirk is showing that there's still plenty of fight in the old girl, after being told the ship is too old and past its prime. But then they got shot by the BoP, and all that build up just rapidly deflates like an balloon zipping about. "Oh well, guess we gotta blow her up!"
It's why I'm not as fond of the stealing of the Enterprise scene. In total isolation, it's nice, but in context knowing what comes later, it feels empty. Which is too bad, because James Horner was killing it!