It's the way they went about it, this isn't the first time they've put ambiguous prompts in front of computer illiterate people.
Before this they had an option where you'd get the option to "Reserve your spot" or "No, later". Picking the latter literally meant, no not now but actually do it without more prompts later. You should see how many iterations they had of their update window.
I work in IT where I deal with the general public's experience with it and it's has tons of issues, in my opinion the upgrade process is utter shit and barely works because I've had hundreds and hundreds of systems come in that need sorting out because of it.
I don't use it; I will when it matures more and I know as a matter of fact some things I need to use won't work. I can't even bring myself to install it on a separate drive. Same with 7 and 8, I waited a year or two. There's absolutely nothing to lose for me waiting.
How is it impossible to defend? I work in IT and know for a fact that the update notification pops up every few days. It's on the user of the PC to keep track of what is going on. If you don't want updates installed completely turn off the update services in Windows or block the ports you receive updates on. It's in Microsoft's TOS this was going to happen, it's on the user to keep up with what is happening to their PC.
You work in IT? Uhuh, doing what? I guess you don't deal with the public at large because you should know better that in this industry in that sector, people aren't good with tech. People who are too afraid to change their ink, or don't even know the difference between windows and ms office.
In the nicest possible way, because so many admit that themselves.
