>It's clear that Apple considers the relative openness of Macs a defect which they're only keeping around for backwards compatibility.
This is not remotely clear. Do you really think Apple wants the App store to dry up because they are the only people left who can develop for it? The Apps make the app store and they know this.
False dilemma; that is not the other alternative. The other alternative is that only a certain set of people bother to purchase the license to create apps, mostly for professional reasons, and plenty of apps are still created. But not by curious teenagers who want to learn about how things work.
This is not remotely clear. Do you really think Apple wants the App store to dry up because they are the only people left who can develop for it? The Apps make the app store and they know this.