I find that I can knee kick at the same range I can leg kick. the Wing Chun lop gerk for example is quite close range. In sparring I still press the knee, I just don't strike it. I don't know that it's so easy for me to change muscle memory so quickly. For JKD however, I believe we should focus on the knee, along with other areas of structural integrity. Wouldn't this be the most simple way to stop someone?