kde-gtk-config depends on gtk+-2 even if only gtk+-3 is used in the system. If user on such system wanted to configure gtk+-3 apps appearance, gtk+2 needs to be additionally installed solely to compile kde-gtk-config with no gtk+2 apps to apply styles to. If possible gtk+-2 support should be selectable at compile time allowing gtk+-3 only installations.
Seems reasonable.
It doesn't seem to link to GTK+ 2 at all, so maybe that dependency can just be removed entirely.
Should be fixed by the distro since kde-gtk-config doesn't rely on gtk2 now.