I fail to see your reasoning. IE6 was (I believe) the default in Windows XP, which people are still using. Should we demand that JQuery support every default browser on every default OS until they're all end-of-lifed?
Firefox and Chrome do automatic updates, and almost never has issues. That's because they stick to standards in an open and transparent manner. Why wouldn't Windows Update be able to do the same thing? Are the Microsoft software developers really that bad that they can't do what the Chrome and Firefox developers can do already?