On one hand less than 2% of Android users even bother to sideload so its probably not as big an issue as we might think.

On the other only 2% of Android users sideload so its no advantage to the consumer. Its not like Google's platform is swimming in legit alternate app portals.

For me the biggest issue is with historic piracy. It used to be really easy to pirate games on Android which is why iOS has a much stronger lineup of premium exclusives. Opening up iOS might scare developers into adding 'freemium' mechanics to their previously paid-for titles, ruining them in the process.