What is the inherent problem with software just being old? Do some of the bits fall off?
The problem is that the web has actually moved on from what was standard practice 9 years ago. There are new methods to make crafting pleasant looking web pages easier and more productive. IE6 is simply too out of date for a large chunk of what is possible to do on the web anymore, forcing web developers to waste time doing their sites two ways. In my case, I build my sites to work in all current versions of browsers, and then spend an additional 30% to 40% of my development time making it work in IE6 as well. I'm starting to think of listing support for IE6 as a separate billing item so that the client can more accurately evaluate how important it really is to keep supporting this cranky old beast of a browswer.