I get what you mean, Forbin... I guess what I'm trying to convey about the models for filming, is that an amazing amount of thought seems to have been put into all the little details that we can't even see unless getting a frame shot. It's pretty impressive.
That said, one thing that started to bug me about post TOS, TMP, and TNG ships was the crazy amount things they just kept putting on ships to add more and more details.
TOS was sleek and very clean. TMP was a more tecky and artistic. TNG started off cooler (with it's colours, shapes, and details) but kept getting more and more cluttered as time went on, leading to Voyager, DS9, et c. Seemed unnecessary at times.
So there seemed to be a lack of cohesive design in ships (inside and out) as time when on.
I suspect that, from TMP on, Trek felt it had to "keep up with the Joneses" on the visual effects front, with Star Wars having emerged as the arguably more dominant genre franchise of the day and providing some stiff visual competition (as well as marketing, merchandising and other new business models). The original art design of TOS simplicity was likely dismissed as "boring" and the rest is history. This is likely one of the reasons why all the Phase II designs (Enterprise, K'T'Inga, etc.) were revamped to contain massive amounts of detail to increase their "scales" on the big screen. To seal Trek's visual fate, ILM and Image-G got involved after the bath Paramount took on the TMP VFX and continued in the tradition of over-teching the ships, starting with the greeble-covered Reliant, shortly followed thereafter by the Excelsior and its Imperial Star Destroyer-inspired shuttlebay and the equally overgreebeled Spacedock, Merchant Vessel and Klingon Bird of Prey. Interestingly, only the Grissom seemed to retain the elegant simplicity of TOS (lending additional credence to the theory that it was an older vessel, along with its low registry number). Sad that it was so weak, underpowered and vulnerable to attack and met a quick death on screen with its mediocre Captain. In the context of this particular discussion, it's almost symbolic in a way...