@jt_rebelo @Infoseepage @GossiTheDog it's important to note that the objection here is that users should not be encouraged to store their own encryption keys on a service provider, as that provider has a responsibility to comply with legal search warrants wherever it does business. Microsoft does not "directly" give anyone keys to data without such a warrant as a matter of policy.
@GossiTheDog is correct to argue that a) it shouldn't be made easy to default to the cloud and b) that ultimately, if you mean to encrypt then you likely mean to own those keys yourself. Don't put them in a service that must respond to legal instruments.