I feel that a big part of the problem is the characters were designed, imho, more as gimmicks than characters. A blind helmsman, a telepath, Captain who doesn’t like kids and was best friends with the late husband of the doctor, young, Kirk-like tough first officer, genius boy wonder, android who wants to be alive.
Again, my opinion was the most interesting characters were the ones who weren’t all that fleshed out, but the plots allowed their personalities to develop organically, giving the actors much to work with, such as Worf, and O’Brien, the two most interesting characters, imho.
As time progressed, the other main characters got more ways to develop their characters, but it was a slow process getting past their tropes, especially in the beginning.