I would prefer it if Kukui had a reduced role in USUM. I didn't particularly care for battling him for the Championship - I can think of several other, far more noteworthy characters who would have been better choices - and, with him holding a chain around my neck from afar as well as with Lillie joined to my arm, I never really felt like I had much of a choice in what I could do.
The sense of isolation in earlier Pokemon titles is one of the reasons I preferred the earlier titles. Having Lillie and Hau in my face I could sort of understand, because they were on an adventure too; it was almost like an RPG party...almost. It wasn't anywhere near of the quality--yeah, I've said all that before.
But with Kukui there as well, I felt like I was on a leash as well. Go where the adults tell you, do what they say, prove your worth to them, etc. There was very little room for actual growth with Kukui watching over my shoulder constantly to make sure I cleared the Island stage and moved on to the next, and it heightened the on-rails feel SM had. He needs to go. Yes, OK, I've been led around Alola by the hand and on a leash. I know where everything is. In USUM, let me explore on my own terms, yeah?