I don't see why some instructors have problems with people using self defence they learned in other classes, unless they think it wouldn't work, in which case can't they take the time to explain why they think that?
When we do step sparring we're not told to use the flashiest moves me know, but rather the dirtiest! Beginners will start off learning just using basic punches and do for a while, but this is so it becomes second nature, some people do find this boring and want to move on, but there is thinking behind it.
After reading posts from various sources and talking to people from different clubs, I don't think there's anyway at all you could call the class I'm in a "traditional" TKD class. We hardly do any sport sparring, lots of self defence and use our hands a lot. We also use sweeps, taught weapon defence, kick below the belt, do take-downs, throws and learn breakfalling. To me this has been what taekwondo is about, it's always seemed practicle, I've been bullshitted about a technique, we're constantly told that in a fight situation that we shouldn't try and pull off flashy kicks and just stick to the basics which have been ground into us. I thought this was how TKD had always been taught and it was recently that it had been diluted, but maybe it's always been weak and what I'm learning is a mix between tkd, bjj and karate. We've even had a couple of converts from the JKD class because they came down and thought our class was more "adpated to real life combat".
I'm hoping bad schools are more the exception to the rule, rather than a class like mine being the odd one out. If that's the case then I find it very sad and can see why people think it's rather limited. but this to me is tkd, it's how I want to learn it and it's how it'd teach to people in the future should that be a path I take.
Respect and Harmony.