Well hmmm, I'm not sure what others will tell you, since there are so many definitions for the term art, it's so subjective. But for me Tae Kwon Do is an art for me because of the way I practice it. in other words, it would be no problem to learn how to perform a kick and pretty much make it functional, I mean after all a soccer kick is still a kick and if you can make it work for youin combat then well, thats your kick. But the fact that I practice these TKD kicks over and over. Trying to get the most power from my kick, applying it in the most beneficial way, learning how to apply it in different situations, trying to get the mechanics just right so that I don't waist energy, making all moves count. This is what I consider art.
A person could practice sparring and become pretty good at fighting even if they had sloppy techniques.
But a martial artist is someone who practices to perfect themselves in their respective individual disciplines.