I note that a lot of "so what" comments start by "I have never been a kubuntu user". Well, if you were a kubuntu user, maybe you'd know that Kubuntu is closer to the "average joe" user than ubuntu. I did the test on several people around, including kids, and they are more "at home" with Kubuntu. I don't really know why. But it seems ubuntu is rather closer to the classical Linux/Unix users (although Unity changed that quite a lot).
And KDE is way more esthetic than Gnome or Unity, but that is a totally personal and subjective statement :-)