Because its foolproof for end users. I have a good, and otherwise intelligent friend whose laptop, until I got my hands on it one year ago, hadn't updated since Jan or Feb of 2014 or so. I have a hallmate whose laptop had auto-updates off on his laptop for no decent reason. There are times for it, but they are few and far between.
Power users, or those who want more control can access user policy.
Also worth noting, Chrome auto-updates silently I believe and takes some fiddling to turn off.
to be honest this situation just shows how irrelevant/forgotten windows for pc has become, I cant imagine this happening a few years ago without a bunch of hackers developing an all mighty tool that gets you the same updating system as 8.1, it just seems that hacker community is gone, they are on android now most likely
its a fair point and very helpful for non pros, but they have gone out of their way to make it a chore for us to control, as I said it still shows a fullscreen annoying as hell notification interrupting whatever you were doing, and to select which updates to get is another problem, they have designed that tool to make it as cumbersome and slow as possible, sometimes it doesn't even list all the updates you see on settings, see for example I wanted to test a keyboard asap on my laptop, the driver was at the end of the list, no way to just get that one for testing and then let the rest update later, had to block them all, then test the keyboard, then unblock them
they should leave all that as is, then hide the same kind of updating utility we had in previous windows versions to choose what to install whenever we want to, if such utility gets enabled, it should override the current system