I remember a long time reading a MAD comic which detailed Walt Disney being unfrozen/re-animated and being toured around the modern day company by an executive. Each stop on the tour was:
"first we create the cutest most marketable mascot we can think of"
"then do you make the movie?"
"no then we design collectible figurines"
"then do you make the movie?"
"no, then we think of clever lunch box designs"
"then do you make the movie?"
....
and after the seeming end to the marketing steps Disney asks again "then do you make the movie?" only to be replied "well actually that step is really expensive and risky, we are hoping to be able to phase it out very soon."
Every time I see SE announce a new sequel/spin-off I think of this. It is almost like creating a new IP to spawn off of is a big hassle that they just want to get out of the way before moving on the their main business.