Using New Outlook on Windows for personal email, calendar, and contact management
It's just a guess but a good one. OL due to age and growth/expansion over time reached a point where more changes/additions would break one or more other parts so the only solution was to start over. The New OL is the non-mobile equivalent of a 3rd party knock-off mobile version of OL. It will take years to make it anything close to what classic OL is like today and they don't want to wait that long before forcing all to using teh new OL so they're making us do it whether it's what's best for the clients or not. Admins love it but that's b/c it's easier for them to admin and provide support for because it does so little. Unlike the other Office products OL has years/decades worth of data attached to it, the users Inbox so while Word, Excel and teh rest don't require a re-start, OL likely did. It still sucks and is wrong to force users as they are doing but it's likely the why.