They'd never be able to get all the actors back, recreate the sets and so on. Remember it finished over a decade ago. Everyone involved has moved on, the actors are a lot older etc.
Nor is there any real demand for it. Yeah, a few die-hard fans might want it, but nowhere near the levels required to justify brining it back. Even a low budget Netfix thing would be pointless.
And doing it would only interfere with the films. Unfortunately, that seems to be where Trek is going to be for a while. That's where the money is, and that's where the attention is focussed.