People who train head kicks are confident with their ability to knock someone out with the speed and power they have developed. Saying they are impractical is a statement made by those who can't do head kicks effectively.

The UFC is the closest representation of brute aggressive hand to hand combat we have that can be studied. Whilst it lacks the eye gouging and groin kick staples of self defence, we still see head kicks under pressure becoming successful, even against well trained grapplers.

There is nothing wrong with training your ability to do head kicks. They develop your core strength, balance and cardio vascular health (something all the obese higher dans could put some discipline into).

I was inspired to take up Karate training thanks to high kicks in Hollywood movies. I've since learnt the finer arts of grappling and positioning my body in combat which I agree is going to be of greater benefit for self defence than employing a distancing combat strategy demonstrated by Olympic TKD martial artists. Having said that though, there are plenty of occasions in 2 on 1 or 3 on 1 sparing where a side kick to the throat or a front kick under the chin (controlled) was the only technique needed to remove a combatant.

In the end you need to develop techniques that match your phenotype (physical shape). Light skinny people might just feel more confident in troubling circumstances with an arsenal of fast and sharp kicks than by learning grappling techniques that would put them at a weight disadvantage and punching techniques that would take years of bone conditioning to be effective.

I don't agree that because ancient karate masters didn't do head kicks they are not karate. Karate-do is a philosophy. Those ancient masters were open to learning new techniques from others overseas. High kicks are just an extension of the karate-do philosophy of never ending learning and improvement.