(edit: forgot to hit reply and made a new message. doh.)
If local network admins upgraded to the latest and greatest IE8/9 we would still be in the same horse shit regarding IE not following web standards. We would be free of "IE6 doesn't have a fucking clue about the box model". But we would be at "IE8 doesn't support canvas (or proper event bubble)".
Microsoft has been using this "network admins don't upgrade from IE6" for too long as an excuse for the mess they keep putting web standards into.
A proper solution for Microsoft now would be to completely ditch IE backend and use one of the current available libraries like webkit. And put in place a IE frontend that can have IE6/7/8 tabs and a proper browser (defaulting to a proper browser). Any other move coming from Microsoft is either PR or evilness.
2. There are just a lot of people that don't install any system updates.
3. There are people with pirated Windows versions that don't know how (or just don't care about them at all) to hack around the 'Genuine Windows' checks. So they don't install system updates.