Many movie franchises get rebooted. Forget the original and just rewrite (and recast) everything. If it did well the first time the name alone will bring people to the theaters. But the name isn't always a guarantee. Especially some studios rely too much on those and forget to invest in quality.
We've seen many failed reboots. People are becoming more susceptible towards the promises and of bringing back their old favourites in a new package. So they need to be offered something more. Something familiar that is not just reusing the name.
Instead of reboot many movie series have worked out a continuation to the old ones. Instead of disregarding the previous iteration the build on top of them instead of starting fresh. Few decades later is a good timespan to get some distance to the original events and give some artistic freedom putting out nee stories. Enough time to introduce a new generation into the cast, but not too much to also bring some of the original cast into the mix.