Hello, first time poster here
IMHO, TKD's kicks (especially WTF style) is still kinda new and evolving compare to other martial arts. I think there is a higher tendency for people to stick to well established (widely-accepted, or popular) techniques, like boxing, MT Kick-boxing, or tactics have frequently won repeatly in the past.
Although there are people who experiment with "new" or less-popular techniques, they also need to accept the risk for getting injuries or losing the fights in order to gain insight of how to improve those techinques. However, how many people are willing to pay the risk? And how many people have the ability to gather what their experiment, and refine/improve that technique? It takes a lot of effort, wisdom and intelligence in order to accomplish it.
Since TKD is still evolving, in my opinion TKD's kicks have a lot of potential.