Someone else mentioned that the kids (what, with their damned loud k-pop music and Tok cloks) are used to using Chromebooks that autosave documents.
Also, MS wants more sales opportunities. If data is on their cloud, they have at least some control over your access of it, and the ease with which it is used in your daily work. It's a pain in the ass to have to manually save stuff, but that's what you'll have to do once you exceed the 5GB free tier limit. I guess you'll probably want to shell out for more space, no?
The good news for your work Mac is that it's your IT and budget departments' headaches, not yours.