Of course it does. And if iOS brings that much value, then charge a license fee for the purchase of iOS.

But trying to recoup the cost of iOS by taking a cut if store transactions is anti-competitive.

If the store were split off into its own company, would it make any sense to Apple for that company to take all the revenue for the value the store provides? Of course not. Let the store compete on its merits and charge for the value the store provides: API scanning, trusted market place, how publishers are treated... And compete against other stores providing those same values and picking their % cut.

Surely the work there is just as worthwhile as on iOS.

They have been compensated, when people bought the hardware. Anything beyond that is blatant rent seeking and anti competitive.

Replace the word Apple with Microsoft and see how ridiculous their stance is. Even Microsoft didn’t attempt to take a cut of every software and digital good sale.

But even if it does, the profitability of Apple's business is Apple's problem. If their iOS store is only profitable through anti consumer (I can't install my own software on my own device) and anti competitive measures (you must give apple a 30% cut off all sales and they have veto power over your app at any point) then perhaps it shouldn't exist in it's current form.