I think the problem, if there even *is* a problem, is simply one of credibility for me: TWOK and TSFS are emphatic about Enterprise being in her twilight years. TSFS especially basically hangs a plot thread on "She's an old ship Jim, we don't need her anymore". So seeing a new Connie being wheeled out at the end of TVH, although a punch-the-air moment on an emotional level, ultimately contradicts Starfleet's previous stance on them not being fit for service any longer. You don't have an obselete car, but still continue to roll them off the production line just because a minority of people have an emotional affection for that particular make and model.
The lampshade we might hang on it (let's call it POPULAR FAN THEORY #1
) is that Starfleet got egg on their face after Excelsior shat itself inside their own Earth orbiting spacedock, and that they had to hastily backtrack on their grand plans to mothball the existing fleet and replace them all with Excelsior clones (until they got the kinks in the design ironed out). But frankly, this excuse itself ignores the fact that Scotty sabotaged Excelsior. There really is no big design flaw, and if they hadn't given Scotty carte blanche access to Excelsior's engines then she might've made mince-meat of the Enterprise.
All of this is basically why we have POPULAR FAN THEORY #2:
That Enterprise in TVH is not a new ship, that she's a rebadged Constitution that has been "gifted" to Kirk for saving Earth and the Federation. But if we're to accept that, it's still something of a dodge. Why refit an outmoded ship with state-of-the-art tech? If it's that
easy to do, why retire the Connies at all? What, exactly, is it about the Constitution Class which Starfleet sees as being so God-damn inferior to the Excelsiors?
Hmm. (un)POPULAR FAN THEORY #3:
Connies didn't leave service, they were just turned in pleasure cruisers like Queen Mary II. The 1701-A wasn't mothballed and broken down, but instead became an intergalactic Love Boat.