Star Wars is... a difficult fanbase, to say the least.
The problem is, there are so many different fans out there, and they all kind of hate each other. No matter what movie or show you like, there is probably another fan who will argue with you, and so creating desirable sets for these fans is a monumental task, even for a company like LEGO.
So they stick to what they know, keeping from trying anything too spectacular, even though maybe that would make them better. Star Wars just has so much unexploited potential to cancel in my eyes, and would hate to see it go when there is just so much left undone (like a second Zam Wesell set or minifigure series).
Of course, this is just speculation, none of this I really know for certain.
Licensing is tough. For some crazy reason, though, the Overwatch sets are actually very well priced compared to them, so clearly it's got to do with Star Wars being as big as it is. Hopefully Marvel won't follow in its footsteps.