The movie was originally planned to have had been mainly about Leonard Nimoy's Spock character, but when Leonard Nimoy himself died in 2015, his son decided to expand its scope to explore his life (the life of Leonard Nimoy) as well. See more
The pendulum swung completely when that first movie came along, from being an actor and character-oriented Star Trek, to an effects-oriented Star Trek. And the feeling was, "we didn't have the money before. Now we got the money, we got to give them a big effects movie." It was all about the ship, the ship, the effects, this effect, that effect, and we're going through this thing. Now, we're going through that thing. Nothing about the characters. So it was frustrating, and depressing, and uh ...