alt Hacker News> just so that grandma doesn't accidentally install malware
That's the stated reason. The actual reason is that they are salivating at the sight of how much money the app store and play store are making. They just don't want to move too quickly for fear of customers revolting.
Really stupid on their part. There was a town with a baker and an auto mechanic. The baker saw how much money the auto mechanic was making, so he sold his bakery and went homeless because he had no car repair skills.