Vitali Klitshcko was former kickboxing champ, got KO with a kick. Put it this way, who would win, vitali allowed to kick or vitali not allowed to kick? Answer is pretty obvious. Boxing skills itself does not make it superior, its the training methods that makes it superior and in general who takes it. Most MA/kickboxers takes the art for self defence or fitness, most boxers in the gym train to compete...you can guess who will push themselves more.

I sparred some muay thai guys recently, they whooped my ass. Im easily the best boxer in the gym but I probably couldnt even beat the weaker muay thai fighters there. That is because they know how to defend from my punches whilst I dont have the natural instincts, reactions, reflexes, counters, defensive manouveres to their kicks. I try a 1-2 and I get a kick to the leg, sooner or later I find myself in a very akward position in how i move in out my opponent, which punches will work and how I get to them.

I've also done martial arts before so wasn't totally new to kicking but havent kicked in a long time.