Because IE6 is the new Netscape 4.7x
I really hope the IE7 team can pull circa-2001 IE6 out of the accelerating death spiral that it seems to be mired in. I guess that's what you get when you inexplicably stop development for more than three years on a product that is integral to the user experience of millions of users on a daily basis. That's possibly the ultimate WTF.
The same thing happened to Visual SourceSafe-- virtual abandonment. Of course, Sourcesafe is used by a heck of lot less people, but the results were just as catastrophic. Although there's a belated 2005 update that will ship with VS.NET 2005, SourceSafe is now basically synonymous with what not to do in source control.
I don't care how big a monopoly you are. Abandoning development on core products is bad business and demonstrates near-total disregard for your customers. I'm really pulling for the IE7 team, but they have their work cut out for them.