I think the best-case scenario would be to come up with something that's new (maybe looking like it evolved out of ENT) but also looks like it will evolve into TOS, as seen in the TV shows. There should be new designs (and aliens), but I think taking advantage of the pre-TOS setting and making it look like the previous generation of tech would work quite well (Think
Star Wars: Rebels to the original
Star Wars trilogy).
And that might be the thing. You can do that with tech, make changes and stuff in a way that makes sense. With aliens, not so much. Logically, they would have the same genome and not suddenly evolve one way and back in a couple generations.
All I said was that I think they're not very popular amongst long-standing fans ... not that every single older fan dislikes them. No sweeping over-generalization... just a regular, ordinary little generalization... I get my impression they're not very popular from coming here and reading posts about them every day.
Hard to say. I hate the first two, but thought
Beyond was a good
Star Trek film and worthy of the name. It's also worth bearing in mind that some people think seeing the franchise from a new angle is fun. Other people aren't too worried about continuity (canon seems to be the main sticking point for Kelvin Timeline haters). Also, for many fans, this is their first exposure to
Star Trek, so this is the "real" thing for them, what the franchise is when stripped to it's most basic elements.
(I can relate; I'm a Spider-Man fan, but was introduced through the original movies and Ultimate comics, not the original
Amazing Spider-Man comics, which are, for all practical purposes, the canonical or "real" version of Peter Parker and company. It's the aforementioned adaptations that define what the character is and should be like to me, what I'm think of as the "real" deal.)
[EDIT in response to
@Hela's comment: Also, this is only one section of the movie's fanbase. Not all fans post here. Also, the Kelvin Timeline's fans go beyond the Trekkies. They include "non-fans" who like movies and have their opinions. So, while I think it's fair to say that the new movies don't have anywhere near the integration into pop culture that the others have yet, they are making their own mark. Also, they're drawing in many fans to enjoy the other stuff, too. So, they're acting as a gateway to the parts of the franchise that some of us prefer.)