This is actually a very very good point.
There hasn't been a single Star Trek series that hasn't started out rough
Honest question from someone who's just getting into Star Trek and going through the Original Series now (slowly): does that mean it should still be the case? TV is going very strong in the last couple of years, with relatively big budget tv shows being able to still be very author driven.
Also, even if all the Star Trek series started rough, did they also all end up improving later in their run? Again, I've only seen the first original Trek season (although I've heard opinions that it's actually downhill after that first one, but I'll see), but I have heard that, for example, Enterprise never really improves.
I don't think it's smart to just accept that all shows just start rough and automatically get better. A lot of shows do once they find their groove, sure, but the talent who could make sure this is good to great right out of the gate is definitely available these days.