It's one of my issues with TOS looking back on it. Few races are actually properly examined Later series, even the questionable ENT and DISC, do a better job
I wouldn't go "down and dirty" but I would definitely do something akin to Firefly but in reverse. Whedon envisoned it as a show about "planets the Enterprise would skip." I would take it and do reverse of this concept, with planets that the Federation has already been and now supports, but with a civilian vs. Starfleet in charge. Yes, it would be a little bit more rugged, in that they are on the edge of explored space, relying on hard work much more than perhaps other colonies would. And show them exploring the different facets of the new world.
I would want the next show to be a 32nd- or early 33rd-century series — ideally, Star Trek 3200, primarily following the era’s Starship Enterprise on exploring new worlds of the week — but also dealing with repercussions of what we’ve already seen about the era. For instance, we’ve already seen that there are human (and presumably other) worlds fighting the “V’draysh”. Why? Especially if, from what we’ve seen, the Federation does still appear to be the good guys? How about this: The Burn devastated everyone, not just the Federation. So a common belief built up over the decades among much of the rest of the galaxy—fed by disinformation from the Federation’s enemies, and then by constant continuing insistence by local planetary cultures that had absorbed it as The Truth—that the aging Federation intentionally caused the Burn, to weaken everybody else, and was only accidentally caught by its own miscalculated strike. It’s nonsense, of course. But half of known space now “knows” it, and Federation members who object that it just isn’t true are often either dismissed as liars and propagandists, or told that of course you’d say that, you’ve been culturally brainwashed… So a lot of worlds, often but not solely Emerald Chain remnants, fight on against the “imperialist, colonizing” V’draysh, citing their crushing of local insurgencies on Ni’Var and elsewhere as evidence of Federation perfidy. (Fact is, though well-meaning and aspirationist, the Federation in this era is necessarily harder-edged than it was in the sepia-toned golden age of the 24th century.) So despite having plenty of allies, the Federation also has to work against this widespread, common, false view of it as potential oppressors. Drama!
Also — much as I (as opposed to much of the fandom) like Section 31 as a story-generating element, we really do need to have the story of how it was ultimately either brought down or thoroughly and permanently reformed. It’d be nice if the S31 movie turned out to be that. For Starfleet to remain the moral exemplar it’s usually played as, it really does need to renounce its War Crimes Division, and to have that happen in the early 25th century.
There's always going to be a super-secret investigatory body. At least for the conspiracy theorist writers. Just look at PsiCorp from Babylon 5.
Oh sure, and they shouldn’t lose that. They’ll probably always need a dirty-tricks department, or even possibly an if-all-else-fails assassination department. But not a full-on secret Gestapo, medical experiments, etc.
What if they did need to eat, and what they consumed was other shapeshifters? Shapeshifter 1: Where's Bob? I haven't sensed him in days! Shapeshifter 2:
I'd like to see Trek continue on from DISCO and stay in the far future. Let's start making new explorations! I think the end of Season 4 set that up well.