That's all well and good. There are a lot of internal corporate applications that were developed on IE6. Knowing that IE6 required workarounds that would break in IE7/IE8/FF3/etc, it would be irresponsible of Microsoft to force upgrades to IE7 or IE8. Meanwhile, corporations are not likely to revisit working apps and upgrade them to IE7 or IE8 - there are better things to do with people's time. So, the sad truth is that IE6 is going to live on as a legacy application, but not one that necessarily must be supported by present and future applications. There are plenty of alternative browsers that can play alongside IE6 in corporate environments and allow web development to progress.
This reply is a bit blunt, but if you're outside a big corporation, it's easy to say 'bad developers, get with the program', which is an overly simple answer that ignores the reality of most big businesses. They want to get things done, and that doesn't always mean doing things 'correctly'.