They know that nobody's going to use it anyway.
The first thing I do when I get a new computer or install a new os is download firefox/chrome, and then download anything else I need through those browsers.
IE8 introduced standards mode. You should not really have to write separate CSS rules for IE today, unless your site must absolutely have IE6 compatibility. Otherwise I leave things broken in IE6 Figure it's best to leave older browsers behind otherwise the web will never move forward.
I'm not a fan of IE but at least Microsoft is improving. Still I don't think it will help bring back any Firefox/Chrome converts at this point.