Roddenberry, the producers and writers had a constant fight with the network about the plots etc.

The networks wanted a 'Monster of the Week' type of show, the production staff wanted a show with decent science (as was projected by some of the better scientists of the time) With as SDAI-1 says, a deeper meaning.
So what we saw, and still see, is a compromise.

Which is the case of almost all media presentations of a lot of subjects.

From science fiction to military action.

I can sit and watch almost anything anymore and within a few minutes figure out the plot, and pick apart the basis for it, including bad science and poor research on the part of the production staff.

Drives my wife nuts, I have to bite my lip and shut up. Or suffer the consequences of an angry spouse.

I now watch a lot of PBS, Discovery Channel, TLC, History and Nat Geo channel. Ok Ok Ok I do sneak in a bit of Sci-Fi channel here and there. (I get to watch Dune, Farscape and old Twilight Zone a lot.)

Most of the garbage on Network TV is a waste of time.
(I have yet to see an episode of Enterprise, it comes on a UHF station we can't get here.)