I'm not so sure about this. TOS and Enterprise are actually outliers from a production point of view in the sense that everything that chronologically came after them basically used the same production assets originally developed for Phase II and The Motion Picture - the Enterprise Bridge that most famously became the Enterprise-D battle bridge among dozens of other locations, the Corridor sets, the various starship filming models created for the movies and TNG, the alien makeup designs developed for TNG and so on. The high level of visual consistency in movie- and Berman-era Star Trek that we've gotten used to and have come to expect is basically a function of 1.) Paramount saving costs wherever possible and 2.) Star Trek being more-or-less continuously in production from the '80s to the mid-2000s.
So I think people who found Discovery's design aesthetics too far removed from TOS for their tastes would have the same problem with a similar-looking series set in the Lost Era. And in that regard, I can understand why the most common bullet point in "how I would've done it differently" lists is setting the series post-Nemesis. If avoiding Discovery's visual language clashing with previous Trek productions is an absolute must for someone, that's the only way to truly do it. Basically, if one has a problem with Discovery because they can't see the technology and the ships in it change into those seen on TOS, they'd find it even more jarring if there was a time in the Lost Era where for example the ubiquitous Excelsiors or Klingon Birds-of-Prey looked wildly different, on both the inside and outside, for ten years or so before being returned to their classic looks.
On the other hand, in order not to sound absolutely negative, The Lost Era would actually be a great setting for a Star Trek series simply because we barely know anything about that era and, just like Discovery's original timeframe, we have only encountered it by having the characters discuss it and of course the occasional flashback.