Most TV shows don't take a season, or two seasons, or whatever to "get good." This is kind of a silly notion that Trek fans seem to have, that such a thing is reasonable to expect and should be allowed for.
In fact, I would argue most shows are at their
best in their first season. That's normally when they use up all their good ideas and then have to scrabble around in a hurry for the next one. Difficult Second Album syndrome applies equally to TV shows.
Stranger Things is about to hit that hurdle.
Pilots, however, are a different matter. Many shows have weak pilots, or pilots that don't really gel with the rest of the show. It's a rare show that hits its stride right from day one, especially sci-fi and fantasy.
Game of Thrones is an exception, but it is a book adaptation - most of the story, character work, etc is already laid down for them in advance.
In short, I will happily give a show two to three
episodes to hit its stride. Two to three
years however is unique to Trek. I think it is symptomatic of the way Trek series are made. Instead of having a story in mind that they want to tell, Trek creators tend to work in broad ideas about the show's setup and just hope that story plots flow from that -
It's a spaceship with a crew, OK, which of the crew are aliens? Which specific aliens and what do their foreheads look like? What does the ship look like? What colour are the nacelles?
This one is set on a space station. It's in orbit around a planet at first, then a wormhole. OK, great. What is the precise history of that planet's religion?
Trek shows are built on ideas, in the hope that stories will follow. It often takes two to three years for this to happen. Take TNG. There are plenty of books out there about the sheer amount of work that went into setting up TNG, casting, sets, ship design, props, effects, blah blah blah. But then their
second episode story is... a remake of a TOS episode. Third is a racist caricature. And so on. Did no-one in all that lead in time think about what this ship and crew they were designing would actually
do?