I'm in two minds on this. As a user, it does irritate me that I'm forced to put all my work on hold to install updates.
However, as a security professional, I think the general population doesn't understand just how critical it is to stay up to date with software updates. Sometimes we have to force them!
It's my computer, you see. It's not yours. You're welcome to buy your own, of course. But this one is mine. That's why they call it a "Personal Computer."
The rest of us aren't going to let you turn the Internet into the modern equivalent of a closed IBM shop, at least not without opposition. There's a history here, one you might be too young to have experienced personally. It's been well-documented, though. Steven Levy's Hackers is a great place to start, highly recommended.
Causing fires in travelers' backpacks is not a worthwhile trade-off for security, sorry.
Neither is getting awakened at 4am by plinks from the OS intending to alert you to the installation of updates. If you're going to have so little respect for the user then just install them w/o making any noise.
That's the thing: both of those views are compatible with my perspective. Contempt for the user may be in the interest of any given user, just like forcing your kid to eat vegetables instead of ice cream all the time is.
But forcibly shutting down a machine in the middle of the day during active usage is a cardinal sin, just about the most fundamental user-hostile activity I can imagine. Microsoft may be right, and there may be a portion of the general population whose computer usage is 100% pointless nonsense that can be interrupted as easily as you'd interrupt your child's videogame to make him do homework. But I'm not in that group, and I doubt anybody here would consider everything they do on their computer to fall into that bucket.
Computers touch _everything_. I'm not an NSA agent or a hacker on a heist team, and I can think of a dozen (non-work) times in the last month where a shutdown-interruption of the work I was doing would have been a big problem.
Which brings me to my tldr: I'm not suggesting that Windows' decision is a generally bad one. I'm saying that it's a poor fit for anyone who considers their computer to be anything but a useless toy.
However, as a security professional, I think the general population doesn't understand just how critical it is to stay up to date with software updates. Sometimes we have to force them!