Totally different since including older ship classes is an artifact of legacy production precisely like the ones you just described (“must reuse expensive physical models”), not the desired state as we move into the future where older CG assets are hard to reuse and creating new ones is almost always required, which also makes it possible to create ship designs for a new era.
"New era"? It's been twenty years, not two thousand, and they're starships, not cell phones. Realistically, starships with minimum planned lifespans of 50-100 years (and I doubt that line in the TNG Tech Manual was written with an eye towards reusing the Galaxy studio model in the background of Star Trek: The Nth Generation) would still be not merely around, but pervasive. The entire premise of Picard depends on the Federation having a limited ability to produce new matériel, but it's realistic to assume they scrapped and replaced tens of thousands of ships, something like eighty years' output, in a decade, after their main shipbuilding facility was destroyed? Now who's stretching to justify production realities in-universe?
We already have four uniforms changes in the span between Nemesis and Picard, isn't that enough change for change's sake for you?