The reason I choose this quote is that allthough he is strictly speaking about weapons it is a danger that many Taekwondoin faces in their studies and training. We rely so much upon the longest weapon on our body; the feet that we often neglect closer range weapons such as our arms, knees, elbows and grappling. Relying on one over the others and specialize is in my opinion not the worst thing that can happen. What is a real danger though is neglecting all other aspects so much that you are no longer able to use the other aspects. You often see this with "Taekwondo players" who are masterful kickers but once you get inside that range they no longer function as fighters.
“You should not have any special fondness for a particular weapon, or anything else, for that matter. Too much is the same as not enough. Without imitating anyone else, you should have as much weaponry as suits you.”