They use MAU because it's a metric that's relevant to one of their primary business interests; online services. It's basically the equivalent of a retailer reporting on their foot traffic. No, it doesn't tell you how much money they're making there are other numbers for that but it does give you a good idea of how much opportunity they have for monetization, just like foot traffic in retail.
I think stuff like Office is reported as pure revenue because volume pricing makes unit sales not especially relevant. Including them kinda would be puffery, because it's very easy for them to give you 13% more licenses "just because we like you."
Well, perhaps I am. I'd be kinda surprised if anyone other than the lawyers and accounts had a say in what goes in to the financials. Do you have anything to indicate PR filters this stuff?
Well, if Bone was trouncing PS4, they may not be getting out of the console business, but whatever the cause(s), that's what their financial reports tell us they're doing. The console business didn't survive the refocus. Maybe it would've if it was doing better, or maybe it was doomed the moment Nadella took the helm, but either way, they're done with it now.
Again, Lumia seems to be getting an even worse trouncing than Bone, so I'm not sure why you're so convinced the score determines whether or not something gets reported.
It's not useless, but yes, it's of fairly limited use on its own. You need to combine it with ARPPU and that sort of thing to get a full picture of the health of the business.
But I'd argue that you're the one who thinks of "XBox" as a piece of hardware, and MS have made it quite clear that the hardware is no longer relevant at all. XBox Live is the portion of the XBox business that survived the refocus. Well, that and the game development. But when they talk about the health of XBox now, they're not referring to consoles in any way, just the network service itself, and the games they're making. Consoles are only mentioned in reference to the effect they have on revenue, and then only because you need to report all significant changes in revenue, whatever the source.