The story is simple. If you scan through this topic you’ll find that general kinematic objects class came around after the KCC. I started writing all this to get an ODE-based character controller, and everything else was added later. So the KCC doesn’t inherit from other kinematic objects for, let’s say, historic reasons. This setup just never done me any harm so I rarely notice it, and thus don’t change it. Although, it might be considered an oversight (at best) of mine, yes.
EDIT:
Uploaded a new version, named 1.2.1, in which the KCC now inherits from general kinematics. It doesn’t make much difference, but I guess since it makes your codding easier, Stoo, it might do the same to everybody else 
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Let me know if I didn’t screw up something when changing that ;D.