Let me ask - does Apple see that as a gap at all?
If I move all of my users in Office 365 to start using the Outlook application and I require the Outlook application in order to connect to mail - I have to have the user do full enrollment because I can't control the corporate data at all in that application because the user installed it first.
I guess I just want it noted that without the ability to take over management of the application or install a separate work-only version of the application, I'm going to have to still continue to require full device enrollment for BYOD.