Again, my opinion, but it being separate enhances the experience to me. On days I have 0 desire to be in the dry park I don’t have to deal with it at all. At KD I hated wanting to do mostly water park and having to carry my water park stuff through the park and the crowds.Maybe, but it's also not physically close enough to have a similar level of convenience to experience both parks in the same day without driving between them.
I can imagine for parents and the lazy people like me that the value of Soak City being integrated into KD makes up for much of the difference in experience.
Now if PRKS added a free and convenient shuttle between their gates so it'd simply be a matter of jumping aboard to hop parks, that calculus may change.