The problem isn't that updates makes things work, it's that updates makes the OS more secure (and can fix bugs of course).
Worms and all sorts of crazy stuff are lurking on the net actively exploiting these known security holes. I actually thought you were joking to be honest....
I remember times, when I needed to reinstall OS - Win98 "times", because "updates" did screw up other apps...
Since then, I don't mess up with "updates"...
Magic word - SECURITY....
I think, even banks, or even Pentagon does care about security of their networks, but time to time, you can read in the news that some bank or even Pentagon network security have been compromised...
But what about a casual user?
What kind of sensitive info do you have on your PC?
Who can break to some user PC if all he has - mp3's or porn?
Some loner who has nothing else to do?
To get Virii - 2 ways - either you go to some bad sites(porn) or via e-mail - sent links or attachments...
Prolly, 0.01% that you can get your security compromised while visiting some very well known sites - news, etc....
And...as in our times as of today..."updates" might improve monitoring of what you do on the net...by either MS or Google or anyone else...
Today many people are obsessed about other people, what other people do..say... - who care, you can even notice on posts of some people even on anandtech forums....
Also, don't forget, that many people have more or less degree of paranoia....