I'm actually in favour of it for a number of reasons.
The TOS era isn't as "fleshed out" as what comes before and after it. We only had 3 years (excluding the animated series even though I love it) to get to know the era, the characters, and the federation in general. This will be our first chance to see this part of history with a modern budget. As amazingly well as the original series has held up over the last 50 years, it is still so dated that for many it isn't easy to be immersed.
All due respect to TOS, of course, for it started it all, but imagine TOS with TNG, DS9, VOY, and ENT's attention to detail regarding continuity, technical concepts, and character development. Sure, Kirk and Spock's friendship certainly developed over time, but it wasn't really until TMP and onward that they became relatable people (at least to my millennial mindset).
Beyond TNG there was so much potential, and DS9 and VOY did a remarkable job in my opinion in fulfilling that potential, each show taking certain aspects of TNG and putting their own unique spin on them. Beyond VOY, well... those damn grey uniforms are just so dark, compared to the vibrant TOS, TNG and early DS9 uniforms. Then, what do we get after the grey ones? Well, Endgame and The Visitor, while both technically took place in alternate futures, presented these ugly things:
I apologize if you like them, but they're just so... I'm not sure how to put it. I want to say ugly but I don't think that captures how I feel about them. I guess you could say I just don't resonate with them. Our other options too are grim, from the Babylon 5 special, to the lazy communicator/rank combo, to, well, whatever the hell Daniels wore:
The truth is, the post-VOY and Nemesis Trek universe is actually pretty fleshed out. Even if most of what we see can be explained away by time paradoxes and alternate realities, it seems that in every possible future we've seen, the Federation becomes massively overpowered, with ships that retain the same basic interface that has been present for hundreds of years.
Early TNG failed in a lot of ways, but I don't consider it a failure. It presented a bright future with a bold new look. The ENT-D was not streamlined; it had no need of feigning aerodynamics. It was secure in what it was. The uniforms were form-fitting and loud, showcasing Roddenberry's ideal of a future where the human body was no longer seen as an object of shame. Men wore skirts, because the concept of gendered clothing had obviously worn off, as it should.
Then, the skirts disappeared (at least the men's), and the uniforms became duller. This, to me, is the beginning of the downfall of Star Trek uniform design. I know there were real-world reasons why this was a necessity (not least of all the physical health of the actors), but something was lost of the texture of Star Trek. I like the idea of the DS9 jumpsuits, but the First Contact uniforms were so drab. This worked with the theme of the film, but not with the themes of Star Trek.
I'm fixating on the uniforms, but I feel the biggest reason why going "forward" isn't really the best idea is that, unless they somehow handicap the federation, and ignore Janeway's ridiculously advanced future technology, the stakes need to continually be raised. We'd need new enemies that were even bigger and even badder than the Borg, the Xindi, and the Dominion! Sequel escalation, really, and I don't find that sort of thing very compelling.
Going back (or forward, from the NX-01's perspective), we have plenty of story to tell. Janeway didn't often mention the ENT-D, so why should we expect Kirk to have mentioned the DSC? Tangentially, I love the idea of a ship that isn't a "legend" in the way the Enterprise or Voyager was. What is more fascinating to me than the crazy space anomalies and what have you, are the mundanities of everyday starfleet life. So rare are our extended glimpses into the lower decks, that there is actually an episode called Lower Decks.