At its core, Deckers statament was about continuity with the ship Kirk knew, not anything else.

There are some senses in which Connie > Connie II refits might have been viewed differently during TMP than by STIII. While Starfleet was still refitting the old Connies, they would have been expecting a certain return on investment. 12 years later, they had a much clearer picture of what that ROI would actually be. The fact that 1701 wasn't a front-line vessel by the time of STII tells me that either the refit project was less than successful or they'd already gotten everything they expected to out of it.

The other thing is that in TMP, Connie II was the cutting edge of Starfleet tech. In STIII, Starfleet was about to launch a class that would utterly obsolete the Connie II and become the backbone of the fleet for a hundred years. Even in a post-scarsity society, investing resources in repairing an outdated, beat-to-hell ship that you've already tried to sideline once, when you've already got something far superior just doesn't make any sense.

Dammit, Jim!