Storage of (paid) license data.
Apple deals with it for first party apps by tying licenses to the App Store, but for any company who chooses to distribute themselves a true sandbox means they cannot store license data or even worse: they have to store it “out in the open” (which is to say: in a location that’s obvious and where piraters can start to reverse-engineer it).
Now, to be clear: I’m very much on the camp of “security through obscurity is not security at all”, but what I am saying is that there’s a significant and legitimate unsolved problem for devs to gripe about when it comes to sandboxes and restrictions.
I have yet to publish any commercial software, but if I were I think I’d go the route of Sublime Text and the fit client Fork which as far as I know stop at local license verification. If my business were so sensitive to piracy that its existence were threatened by it I’d probably make my main product an online-only subscription instead.
I’d like this a lot as well, but expect it to come with the usual griping from devs about desktop OSes improving their security models and/or giving the user more control over what third party software can do. Anything short of full access to everything seems to be seen as tyranny.