New Trek tries to be more of an action film or a teenage drama, which may work in drawing in younger people, but it alienates the older fans who, like it or not, still carry the potential success or failure of this franchise. Those older fans are still the ones who cherish the older material and may stick around, hoping, things pick up or a crumb is tossed their way. Executives mistake this as being in support of the directions they want to take the series, and thus a vicious cycle begins.
That said, people forget the older series had some kooky or flat out cringe episodes and moments. Star Trek: The Next Generation, excluding a few episodes, is said to have an agonizing first two seasons to plow through to get to "the good stuff". Maybe these new series need time to find their footing, so I give some leeway here. I'm not really expecting much because what makes Star Trek for me isn't flashy space battles (though they can be fun) or fantastic makeup, it is the ability to stand around and talk...
In my opinion, some of the best scenes in Star Trek are when the cast talk - with each other or to their foes. New Trek can look as glossy as it wants to, cater to a younger demographic, but it seems to almost always fail when it comes to what - again, in my opinion - makes Star Trek: conversation. Not just random dialogue, but actual conversation. New Trek is either not capable of providing stimulating conversation or it doesn't think most of the audience wants that. The first shows a lack of talent, the second shows a lack of respect.
I'm not a science major but the shows, at least the "older" ones, did not talk down to me or expect me to accept casual lingo. When I try to watch New Trek, I feel like the showrunners believe me to be too stupid or too apathetic to care about the quality they're shoveling.
Edit: typos
