I assume the actors that play the captains all had a powerful influence on how the direction of their series went.
Shatner: Pissed that Nimoy's Spock was getting so much attention, but couldn't do anything about it. TOS was changed to being about Kirk and Spock friendship to give both actors enough screen time. Doctor was made the third part of trio due to the actor's talent.
Stewart: Pissed that Gates McFadden was forced to leave, had his part along with fanbase in getting her back. Wanted Action Picard in the movies, got that.
Brooks: Liked the Jake and Sisko family relationship so we got a bunch of that. Also thought racial issues for some reason would still be important in the future, so we got the bizarre "Far Beyond the Stars" and holodeck episode where Sisko complains about how blacks were treated in the past.
Mulgrew: Pissed that Ryan's Seven of Nine was getting so much attention, but couldn't do anything about it. VOY was changed to being about Janeway and Seven friendship to give both actress enough screen time. Doctor was made the third part of trio due to the actor's talent.