The Star Trek: The Next Generation films had this problem. Jonathan Frakes, the actor who played William Riker for 7 seasons on the television series, was given the director's job for TNG movies #2 and #3 (movie #1 was a crossover with the original 1960s Star Trek). A director unrelated to Star Trek was given the nod for movie #4, but the film did poorly and effectively ended the TNG franchise.
It would have made sense to keep the same director-- someone who had been part of the franchise for 15 years and done 2 successful movies, right? But no, the producer wanted "fresh blood," and so picked the director who made Executive Decision, the movie with Stephen Segall on all the posters but who spent only the first 10 minutes in the film. (I'm still bitter.)
So an answer to your question is, "Because of producers who base their decision on their 'gut' or 'feelings'."
MultimediaMusings t1_iyf6ti3 wrote
Reply to ELI5: Why does a single franchise change directors so much? Wouldn’t it be better to have the save director for every movie? by cute_brute
The Star Trek: The Next Generation films had this problem. Jonathan Frakes, the actor who played William Riker for 7 seasons on the television series, was given the director's job for TNG movies #2 and #3 (movie #1 was a crossover with the original 1960s Star Trek). A director unrelated to Star Trek was given the nod for movie #4, but the film did poorly and effectively ended the TNG franchise.
It would have made sense to keep the same director-- someone who had been part of the franchise for 15 years and done 2 successful movies, right? But no, the producer wanted "fresh blood," and so picked the director who made Executive Decision, the movie with Stephen Segall on all the posters but who spent only the first 10 minutes in the film. (I'm still bitter.)
So an answer to your question is, "Because of producers who base their decision on their 'gut' or 'feelings'."