I'm glad to see successful apps exiting The Mac App Store, and I hope others will follow. Unlike its iOS counterpart, which is great in many ways (new app discovery not being one of them), the MAS has unfortunately done more harm than good to the once-thriving indy Mac app-development scene. It offers a low cost of entry, but also encourages "pump-and-dump" development, in which developers are actively (though surely…
I know if they did they'd lose me as a customer for anything other that (maybe) phones, but maybe they don't care about that market.
The only way they wouldn't would be if they grew up iOS into something you can do real work with -- allowed end user app installation, emulators and VMs, containers with full Darwin installs that could run homebrew, etc.
It could be done, even without sacrificing ordinary user experience -- just hide the advanced stuff from regular users and require a little magic incantation to unlock it. But it would run counter to the padded room you-don't-own-your-device philosophy of mobile so I can't see the iOS team going that way without being pushed from above.
Of course they have been updating OS X fairly well, so maybe not. Maybe the poor App Store experience is just like the poor Podcast app and other things -- an internal problem with motivation, direction, and focus in certain areas. Organizations can easily forget about things that are important but not 'hot'.