The Hornets current ownership values shooters, including GM Kupchak who places a very high premium on it which is how you get Brandon Miller above Scoot Henderson. While Kuminga isn't exactly known for his shooting he's got all the potential there and is a plus defender.
Ben Simmons even before his mercurial nature fits that Charlotte scheme not well at all given he's made exactly 5 3 point shots in his career, however, but if healthy they may just flip him later on if not they ride him out. He's marginally more expensive and an extra year over Parsons but the Hornets are not exactly playoff bound (hopefully they know that).
They send a top 8 protected 2027 pick to the Warriors who get Dariq Whitehead a promising wing , the Nets get out of the Simmons contract for a wing they like, but lets face it they picked him after Clowney for a reason and the Hornets chip in minimum contract JT Thor.
Cap Wise the Warriors do pick up some space and while moving on from Kuminga isn't ideal this is sort of a better option for them team glide wise.