I can understand why someone don’t want to use GNOME, because the defaults can suck for some people. And not everything is configurable. But KDE? Can be configured about anything imaginable. While I understand that not everyone want to go full in to learn everything, I still don’t get the default setting for a simple switch like double/single mouse click is a big deal not to use the environment.
If you really like KDE and are used to it, then you won’t change to something else just because the next update changes the default value (for new installations only BTW) of mouse click setting.