you just cant get enough power into hook kicks.
Spinning hook kicks have power to spare no mater what hight they are done at (remember Andy Hugs "tornado kick" KO vs
Mike Bernardo´s leg in the 1996 k-1 final?), but then you got all the problems of spinning techniques instead.
Ordinary hook kicks are much to light to do any real damage. If you use it you have to hit with the heel to the head. using the sole of the foot (like is common in point tournaments) is useless, and hitting the body is more or less useless using either heel or sole.
And if you hit, and dont KO the opponent with a perfect hit to the temple, you are probably left standing more or less with your back facing the opponent. the instant drawback is not as easy if you tries to put followthrough into the hit.
It has its uses, but it is a very low % effect technique.
Bill Wallace was good at it