Now the 1701-A in TFF is another kettle of fish again. There's no Earthly reason at all why they had to send that
ship. Sure, Kirk and crew were assigned to Enterprise, and Admiral Bennett clearly wanted their unique experience, but given the fact that 1701-A is clearly not ready for service in that movie, it would have been more logical to assign them to another ship for the duration of the mission.
You're mistaken. 1701-A in The Final Frontier is
fundamentally ready for service. It's embarrassing to have glitches in the turbolift doors or the ship's log recorder, but none of those are essential systems. The only mission-critical system that wasn't working was the transporters, and those
were touch-and-go, with a considerable chance that they'd be working by the time they were needed. And since there were acceptable alternate methods of doing the rescue that transporters might be used for, even those weren't properly mission-critical, just, darned convenient.
the Enterprise had working transporters, then how would the hostage rescue on Nimbus III have shaken out? Specifically, how would what's-his-name have taken over the ship after all?)
That's a good question.
Maybe the 'transfixed' hostages would have been pawns in some kind of sham prisoner-exchange type setup that sees the Enterprise drop her shields long enough for Sybok or his goons to beam up covertly?
Regarding the 1701-A, you are correct that she is
mostly operational. But if we take the hypothesis about it being a renamed former ship as fact, then perhaps the upgrade/refit process (she looks substantively different internally in STV than she did in STIV) has created incompatabilities within the systems? Whatever case, I'm still not convinced at all that she was "flight ready".
The exact exchange between Kirk and Bennett is:
ADMIRAL BENNETT: Now I know Enterprise is not exactly up to specs...
CAPTAIN KIRK: With all due respect, the Enterprise is a disaster. There must be other ships in the Quadrant.
ADMIRAL BENNETT: Other ships, yes, but no experienced commanders.
A clear implication from Kirk there that the ship isn't ready. It might be functional
, barely. But service-ready?
To be honest, I still don't buy Bennett's reasoning. If other ships are available, then parachute Kirk into one them if his experience is so essential to this mission.