Configurability is the Number 1 reason to run Linux on the Desktop. KDE's number one selling point is Integration. There is no better integrated desktop in the world and that message is lost to 99% of people. I find that I use two desktops the last 5 years. KDE or i3 (tiled desktop) but my applications are always KDE even with i3.

I think that KDE has had so much FUD thrown at it that people just have a negative view of it right away. Sure 4.0 was stated as a Beta and every distro put it out (When KDE stated it wasn't ready for that) and everyone Nuked KDE till about 4.7.