Hollywood is extraordinarily risk-adverse. They want a safe, predictable movie that will make lots of money. They want known "brands" and "franchises", they want long-running film series that are always hits.
The stream of reboots, remakes and sequels all fuel that.
Some sequels are a reboot/remake in all but name, taking a long-dormant film series and hauling out a few of the actors to do one more film so they can get more out of the IP, and maybe try to hand off the starring role to a new generation and start a new series. That's how we got a 6th Rocky, a 4th Rambo, a 4th Indiana Jones, and why Disney is making a 7th Star Wars (and why they paid George Lucas $4.3 Billion for Lucasfilm, so they could have Star Wars and Indiana Jones as film series they could own).
A while back, Simon Pegg said some things about the writing process for the 3rd Reboot Trek film. Paramount doesn't want a traditional Star Trek film, with all the thinking and dialogue and complex plot. No. Paramount is envious of the Marvel Cinematic Universe and wants their Star Trek films to bring in Avengers-level money. They want Star Trek films that are big-budget, big "event" films that make over a billion dollars each time, and they've made it clear to the writers they want a typical Hollywood action-adventure film, and just graft Star Trek costumes/sets/plot elements (because they sell) onto the standard action movie and hope it hits it big like Marvel movies get.
That's what it comes down to, Hollywood wants predictable, highly profitable movies that have almost cookie-cutter uniformity, with the "brand" or film series bolted on for cosmetic purposes. Whether it's JJ Abrams generic-action-movie Reboot Trek, or JJ Abrams generic-action movie Disney Wars film, it's all the same to the Hollywood machine.