I suppose it makes sense for some, but I can't get my head around why people want to put their customers on 365 and then never see any future renewal profit.
I look after one company that has 50 or so mailboxes spread over 8 locations. I considered a hosted exchange as £6 / month / mailbox doesn't seem much, but scale that up to 50 or £300 a month and suddenly the costs become significant. In less than 18 months it becomes cheaper to buy a basic server, exchange and cals and self host.