I just leave my key printed out and taped to the side of my computer, in case I ever need it. But seriously... for the vast majority of users, having it backed up to OneDrive is a great, great thing. I'm talking about the 99% of computer users who don't really know what this stuff is or how it works. For the rest of us, we can always follow the instructions
, remove the key from OneDrive and ALSO change it to a new key.
Incidentally, I understand how all of this stuff works, and really don't care, personally. I use Win 10 in a VM for work purposes, and don't store documents there, but I am using a similar feature on my main machine which is OS X. I do store my recovery key in iCloud. If my device was stolen, and they hacked iCloud, or social engineered their way in, they'd get banking information, credit card data, tax returns. I get all that. To me, there's such a minimal risk (the chance of my laptop being stolen is small. The chance of it being stolen by someone with hacking ability even smaller. The chance that someone with all those skills cares about my data is even smaller still) - I just don't care.
This system is just fine for almost everybody. And the few that it isn't good for (not counting corporations who ought to be on Professional or Enterprise, and aren't subject to this system anyway) - they are smart enough (hopefully) to be here, and if they couldn't figure it out on their own, they've now seen 100 people link to 50 different blogs instructing them how to reinstall Windows without a Live account, decrypt and recrypt, remove the key from OneDrive, etc - there's half a dozen ways out of it even if you already had it happen to you and OH KNOWS my key is on OneDrive.
I suppose a non-technical leaning child pornographer may have a problem one day stemming from this. Good.