Most, if not all, modern martial arts has roots in other martial arts. Aikido is derived from Daito-ryu Aikijutsu, Judo is born from Jujutsu, Shorinji Kempo is basically the Japanese version of Shaoling kung-fu with add-ons from several Japanese martial arts, Kendo is a modern point based competitive version of Kenjutsu, and the list goes on.
And the mcdojo problem is not unique to taekwondo.
Basically it's a great sport martial art. If some people have delusions about it, so what?
The art itself is not at fault. It is the people who degrade the art and water it down just to earn a buck who should be banned, not the art of Tae Kwon Do.