It should know when to be dark and when to lighthearted and fun. If it's all dark, all the time, then people are probably going to tune out. Nothing makes me stop watching a show quite like likable characters getting screwed all the time for no real reason beyond drama.
Too be fair, there a lot of dark shows on TV that people like and get a lot of critical praise, but Star Trek should not be as dark as Game of Thrones or Breaking Bad.
I think a new show will at least have to get with the with the times a bit. Less technobabble and fewer morality plays where the situation is black and white and the "bad side" is represented by a silly cartooinsh villain, either have moral dilemmas that actually gray or if it is black and white, show why something is bad in all its ugliness. Chain of Command showed torture in all its ugliness and that was effective. Also better continuity through out the show would be good.