There must be something, legally, that can be said here.
Leaving that aside, and also leaving aside any complaints about this (I think they've been covered well enough by those above), this is not a good look for Microsoft.
What does it say for your latest and greatest if you feel you have to force it on people and are being increasingly sneaky about it?
Going back to what's wrong with it, one of my (Win 7) laptops runs solely via a 3G dongle. It's not my main PC and I use it primarily for remote access to work and e-mail when I am away. My plan is 2GB and costs $30* per month. If this update downloads when I am not expecting it, who is going to pay for the excess bandwidth?
Now, I am an IT bod so I have the knowledge to sort these things out and I usually update the laptop when connected to a fixed network but not everyone has that skillset and knowledge.
If, as a tech 'guru', you setup a PC or laptop for a friend or family member who has little to no IT knowledge, you would generally enable automatic updates, excluding the optional ones. You know they're not going to understand it and won't do it themselves and you want them to be secure. You certainly don't want them turn on the PC one day and find a new OS has been installed!
* - Or there abouts - it's bundled on the same account as my mobile so I don't really pay much attention to it.