The App Store is more like a food court where Apple is the owner of the mall. They built the mall, they promoted it, they clean up the floors and pay the electric bill. And if they want to sign a contract to get McDonald's in their food court but part of the deal for McDonald's is that there's no other cheap burger places then that's up to them.
The owner of the mall decides who else to offer the stalls to and what the terms are and if those terms are too onerous than they will lose business because people will shop elsewhere because of the bad selection.
What we need is to decide whether we, as a society, think what Apple did is OK. That’s it. If we think it’s OK, then we console the developer. And if we don’t, we pass laws to keep Apple (or anyone else in a similar position) from doing that.
All this food court / McDonalds analogizing really can get you only so far.
The owner of the mall decides who else to offer the stalls to and what the terms are and if those terms are too onerous than they will lose business because people will shop elsewhere because of the bad selection.