I think TKD is a like most other martial arts, in that it's effectiveness depends on how it is used. I did not study TKD here in the US, but in Africa, so my training experience may have been a little different, but I found that many of the basics I picked up as a kid translated, more or less, to the other arts I learned afterwards.
We did have full contact training/sparring, so I think we were much better prepared for actual fights. But at the first national competition I went to as a student, even the high level matches looked, to my admittedly noobie eyes, very inelegant. I kept thinking, why aren't they using this technique, or that kick.
These matches looked nothing like the stuff you'd see today if you watched a professional TKD tourny. I kept thinking this looks more like a brawl, with some kicks and punches strategically thrown in.
After I had my first few matches, I understood why. Many of the things we were taught didn't work so well in practice. What I learned back then, was that what and how you are taught it isn't so important as much as your ability to use your head, use what works and discard what doesn't.
There are a lot of things I've been taught, in almost every martial art I've trained in, that I would never actually use in a match or a real fight. That doesn't make any of the arts I've studied stupid or worthless, because there are still many things I've learned from each of them, that was very valuable.
So even if TKD instruction in the states is lacking, it does not make it valueless. At the very least it's good for some of the basics, people just have to realize that a competition sport is not a self defense sport, go to the right instructor/dojo for what they intend to use use it for, and pick out what does and doesn't work for them.
That was a good summary of what I've been trying to tell people since I got here.