Universal decided long ago to build a Harry Potter theme park; they just decided to divide it up between the two existing theme parks, to phase it in one sectionat a time, and use the income from it to replace older rides and to add a water park and eventually a third theme park. For people who don't like Harry Potter, I get that it's annoying to see the Wizarding World taking over old rides, but those rides were in need of replacement anyway, and for every WW attraction added, other attractions are being added that are based on other properties.
If they had built an entirely separate Wizarding World theme park instead of building it as a train-connected theme park in the midst of 2 older theme parks, all the money earned would have gone purely to the WW instead of towards refurbishment of older attractions and the addition of many of the attractions that have been built the last few years. Is that really what people would have preferred,or do they just not realize that the approach Universal chose is a win/win for everyone?