If you include the obvious caveat that you are specifically referring to current day Sport Taekwondo, and in a system where 10 year old children can be blackbelts, where a limited understanding of the art and a mere fifteen years of training is enough for a 4th Dan, then you may have a point.
Know though, that TKD is an incredibly varied set of realated art forms and sports, from stuff that is incredibally close to the original Shotokan, to stuff like WTF sport schools, to stuff that has drifted closer to pre-Shotokhan Okinawan styles.
I mean, heck, my own TKD training is predominantly hand techniques, close in, with lots of grabbing. You assert that, for example, TKD can't deal with an underhook. Personally, as another 15 year TKD practitioner, I definitely feel more confident fighting in an upright grappling range than I do at head-kick range. Yeah, I've got some kicks, but no they are not the backbone of my style.
So before we do the whole "MMA sport is real fighting TKD is just a dexterity game" thing that young martial artists or those with limited understanding or experience have decided is vogue, let's remember that TKD is a vast array of arts, and that there may be more to it than you were taught or understood, especially among more traditional or unaffiliated schools.
Now, don't get me wrong, I like MMA, I think it's a great game. I love sparring with sport fighters. However, to think that a sport in which fights are expected to last 3 rounds is the closest you can get to real violence betrays an absolutely
immense misunderstanding of what violence, especially the scary stuff, actually entails. (Hint, it's not sparring, and it's also not a typical bar fight.)
So yeah, train for MMA competition, and more power to you. Or, train BJJ, just realize that not training stand-up
is every bit as much a gap in training as not training close fighting or ground. Or train older TKD and have fun with limited outfighting, extensive close striking and upright grappling, and limited ground work.
But don't mistake Olympic style TKD for it's early-mid-twentieth century roots.
