Okay, then.
I'm going to try really hard not to sound pedantic but I make no promises. Suffice to say this is my take on what I have seen, especially with TMP vs. TOS vs. DSC.
For starters, I am struggling with how DSC "invalidates" the TOS pilot. One, as established by TMP, it apparently only takes two years to fully refit a starship. DSC takes place ten years prior. Second, DSC has done nothing to change the story that WNMHGB tells, nor the impact upon the characters. And, for me, as much as I love starships and uniforms and tech that stuff the characters matter more to me. If events take place in the 23rd century then that is where they take place and that's OK.
Look at it this way; if we strung all the Short Treks, DSC, and "The Cage" together in chronological order, it looks like Starfleet was constantly rebuilding the
Enterprise between two designs every few years. I don't blame people for not liking it; I personally really, really wish that they'd left well alone for anything before "The Cage," since DSC
Enterprise before that is where canon gets really broken with out much to paper over it.
Finally, GR already gave us a convenient out for visual discontinuity. TOS is a dramatic recreation in-universe.
Yeah, he put that in his novelization of the first movie, the same one he also told us was not canonical. While I think that "Ex Astris Scientia" fan site guy has been turning into another James Dixon over the years, I do agree with him that visuals are a part of canon (where we disagree is on whether it's okay to be angry over a TV show for not checking off every single box).
I get it-DSC will catch flak for merely existing and taking on a time period previously established. For me, the most important part is the characters and telling their story. Am I convinced that DSC fits perfectly? Of course not, but neither does TMP or TWOK, in my opinion. But, am I invested in the characters to accept those visual discontinuities? The answer is a firm yes.
Well, that's a healthier opinion. Wish that there was some happy medium where the "in-universe" canon and continuity elements could be discussed without people overreacting like the shows are some sacred text.
Re-read my argument about how nothing changes so completely in two-and-a-half years. It doesn't. 40 years of living tells me this. If it was just the Enterprise that changed, fine. But they changed everything else too. The best I could rationalize it in the past (before Discovery) was that the TOS and TMP look overlapped with each other for a while. I didn't entirely believe it, but I went along with it anyway. I suspended my disbelief in the literal sense of the phrase.
I submit that most people are okay with the changes TMP made because those changes happened either when they were very young or before they were born. So they take those changes for granted.
I don't see how TMP could "change" stuff we'd never seen before (and the only actual changes where explained in the context of the story). It was mostly additive, not revisionist. (Course, I don't have a problem with overlap; in fact, I welcome it. Heck, I would've loved to have seen DSC ships interacting with TOS ships onscreen, like in "In a Mirror, Darkly" [ENT]).
Even neverminding that, in TNG, DS9, and ENT, the TOS Enterprise wasn't a ship that was from the same era. It was from another time. Either from 100 years earlier (TNG and DS9) or from 100 years later (ENT). The original Enterprise and Discovery are supposed to be contemporaries of each other. To have the Discovery next to the TOS Enterprise unaltered doesn't work because they don't look like they're from the same time. DSC already established how their depiction of the TOS Era looked, so it was too late to have the Enterprise looking as it used to be.
If Discovery had the TOS aesthetic from the beginning, then I'd be okay with seeing the Enterprise look like it did in TOS because it would fit. Intra-show continuity trumps cross-franchise continuity. The show has to look consistent with itself first and foremost. They chose, from Day One, not to look like TOS, so they're stuck with that decision. At least with DSC. Maybe some other series will do something else. I don't think so, but the precedent is there now.
I don't see the problem with having other different-looking ships. I mean, most of them were brand-new designs, not a replacement for stuff we'd already seen. I can picture DSC ships being around with TOS ones, since different designers makes sense in-universe; a single ship constantly changing between two designs, doesn't make much sense in-universe.