I think the problem is, as stated before, the defaults. I thought KDE sucked at first with the default installation from the Ubuntu repositories, but I played around with it more and more and took a liking to it. I found more and more useful features, and I configured it to fit my ideal work flow. I don't really like using anything else any more (especially Windows) because everything else feels far too restrictive to me. I've got my KDE desktop configured such that the applications I use regularly start up exactly how I want them: dimensions, position, workspace... hell, I even have my IRC, email, and RSS clients set up to group together into a single window with tabs separating the applications! And I've got the menu-bars and widgets I need exactly where and how I want them.
But that's the "trouble" with KDE. It doesn't give you something amazing right from the start, it gives you the ability to build something amazing for yourself.