While I would agree (and some would make the point) that Microsoft does this to benefit mostly Microsoft, it's still GPL'ed code that is now part of the greater Linux kernel codebase, so good on them and everyone else.
Basically I don't think that enlightened self-interest is a bad thing.
Well, of course. I would wager all the corporate contributions, and a good chunk of the independent contributions are contributing to add features they need.
I agree, though, good on them for contributing, and even better for making a substantial contribution, instead of a token gesture.
The irony is, there is a benefit to Microsoft for working with open source: if dosbox and wine become good enough to support their legacy software, they can end-of-life a large portion of their compatability codebase that they drag along with each version, and keep the compatability effort to a stable, free platform written for that purpose.
NTVDM is unavailable in 64-bit Windows, but XP Mode uses 32-bit XP, so it can be used to run DOS software. (Though there will be trouble if you try to use it to run DOS games.)
I'd say it's just good enough for the most useful 16-bit Microsoft utilities.
I've also seen some quite trivial programs fail completely in DOSBox due to imperfect compatibility.
The initial release of the iPod only interfaced to a Apple computer.
Oracle makes a lot of money.
Microsoft likes money.
At some point being more open may be a Microsoft strategy.
Certainly I think they would be more successful if they were more open.