it's utterly ridiculous and totally irresponsible to dish out a 10 GB update.
Indeed!
About the reason(s), sorry but so-called security is just a bait. It smells more like some AI **** inserted into the app and, like I already said, a bunch of spywares and logical valves to remotely lock up some functionalities on demand.
Whatever is proposed, it's up to M$ to solve the issue they created post-contract, not to the customer.
Well they just messed this one up big time. Lost control of how upgrades work. You can see how it happened but it shouldn't have happened in the first place. Quite a bit of miss direction out there on how to fix it.