This one is confusing. Walled Gardens have certain negative traits. At the same time, it’s difficult to say Apple doesn’t have the right to run their ecosystem they way they have currently designed it.
If I pay for a general computer, I should be able to run whatever code I want on it. Apple should have no say in what I compute.
If you want to frame it in contract terms, this is like signing on the dotted line for a mortgage ("enter into the contract, buy the phone"), then some time later saying "this payment is too much" ("I don't like this bit, I want to pay less"). It doesn't work that way.