I am not really concerned Microsoft is downloading files from computers, but I am concerned if they technically have the ability to do so. If it requires an encryption key or some kind of password, these have a tendency to leak. If it is limited to a certain group of people, who's to say none of these people can be persuaded to sell your data? And would it be acceptable if the three-letter agencies can start snooping not only in the cloud but also on your own computer without you knowing?

And who is going to challenge Microsoft on this in court?

You lot, by the strength of the hatred I'm reading, here.