What If Apple Emulated Windows 8...

... And made all secondary first party apps on iOS (Mail, Weather, etc and NOT Phone/Messages) deleteable and downloadable from the App Store, and allowed users to completely replace them with another app of their choice? It would also make it easier for Apple to periodically update those apps, rather than with a new version of iOS. I think it's a lot better than the "set this as default app" move, as I don't really think people will need more than one app for the same purpose, though that option can always be left open to them. It would save a bit of space on iOS for people to delete apps they don't want (Stocks, and the like. A lot of people I know don't even touch it). What do you think?