one thing that helps a kicker is the range at which they can fight if you have a good front kick or side kick your opponent shouldn't be close anough to take atvantage of you being off balance also if you are a good kicker you should be on balance after a kick and even be ready to counter if he rushes in. Also leg kicking really could slow down a boxers footwork and bobbing and weeving can play into a big kick. and as far as kickboxers not taking punches well this is becouse of the talent pool being smaller not becouse of the style being able to take a punch has alot to do with the indavidual ( tyson knocked out alot of boxers but that doesnt mean they couldnt take a punch)