I've always leaned towards this notion too. But, let's be open-minded about it; it doesn't have to be the only possibility. Canonically, all we really know is that the Enterprise
's appearance changed significantly when she was probably 25 years old, yet ships that are at least this old, on designs that we know to be older, were never seen to have changed so drastically.
The way I see it there are these possibilities, not all of which are mutually exclusive:
- The Enterprise was so important, symbolism necessitated her refit/preservation
- The refit process as seen on the Enterprise is actually fairly common, and it's a coincidence that we haven't seen it
- The refit process is fairly easy, but the Federation generally chooses to simply build new ships instead
- Refits like this were once typical in the 23rd century, but technological progress changed somehow so that by the 24th century such drastic changes were rendered unnecessary
Agree with all these. The fast is, we saw too few of the refit-style constitution type ships in the movies, and know even less about their backstories, to be able to conclude one way or another. Additionally, a problem with the political forces is that up until TMP, the only notable think we know that Enterprise did was make it back intact from the five year mission (not that there aren't some undocumented adventures that equaled or rivaled that feat). The refit happened before the VGER incident.
Though I feel that there was some MAJOR political forces at work in the wake of the Genesis incident that combined with saving Earth in TVH, greatly affected the Federation for many years. Of course, that is just my own personal continuity -- we unfortunately are given comparatively little insight in the political machinations of the federation outside of the areas affecting our intrepid crew.