But I suspect that even if you're idea was suggested, it probably would have been turned down out of hand, due to having to design a new Enterprise, which would only be used for one episode. True, they could have gone with making the F a tease like they did with the Ent-J, but I'd think fans would have expected more, as we are talking about the Enterprise after all. I'm sure that the executives didn't want to have the Enterprise-F designed quickly, only for the fans to be unsatisfied with it, and they sure weren't going to give a lot of time to design a brand new ship (let alone the interior), so... Even though I agree that it would have been a better idea, it would have also taken more time and expense to execute properly.
Actually what I meant was that what we saw as the Enterprise-J, should have been the Enterprise-F. Drexler already had a CGI model made of the ship for "Azati Prime" (although all we saw of it was the underside of the saucer through the window). By the time we'd have seen it in "TATV," it would have been fully fleshed out.
And as for the interiors, I don't really see much difference between building sets for the Ent-F as opposed to building sets for all the other ships we saw in the show.
Also, by TATV, everyone pretty much knew Star Trek was dead for the forseeable future. So why the heck not give the fans a treat by designing a new Enterprise? Yeah, it would have just been for one episode, but by that point, so what?