I'm not a fan of high kicking. Looks great in the movies... but...
I did Tang Soo Do Moo Duk Kwan a long time ago too...
But you also have to remember, that if you're fooling around with friends, karate guys can't really punch people, so you would have to judge them in a real fight. The same goes for Kung Fu.
Kung Fu is particularly deadly, because almost all strikes are to the enemy's throat, eyes, or groin. You can't do that in a "rassle" with friends, nor even in a competitive sport. Go to the link I posted earlier. Check out the speed of that guy. Imagine him trying to machine-gun punch you in the throat... all the while, he holds your hands down. Watch his technique... that's kung fu. No high kicks. No spinning acrobatics. Straight "Ling Wang Wan" puches to the throat. Fight over in seconds.
High kicks tend to be a trademark of the Korean systems. The point behind teaching students to kick high is improve flexibility and endurance. Going through a one hour class focused on high roundhouse kicking drills is great way to burn calories. But, I agree that for self-defense purposes, kicks should be no higher than the waist.