No one said anything about just doing a 'good' job, you seem to have come up with that yourself. Excellence is in the original forms (most all forms if done correctly).Recently, I've switched from TKD and HKD to an art that is much less rigid in training: BJJ. In BJJ, there is so much to learn that it can't really be broken down in the same way a TKD curriculum is. Instead, you learn some things by drilling the "move of the day", and you learn others just in sparring and getting feedback. The move of the day is often tied to a concept each week, which is tied to a larger concept each month.
In BJJ, this manifests as: in May, we're working on lasso guard. The first week we're working on sweeps, the second on passes, and the third on submissions from lasso guard. And during the first week, we might learn a sweep on Monday, refresh it on Wednesday and learn another, and then learn a few others on Friday.
The way that might work in TKD is that May is spin kick month, Week 1 is back kick month, and we do different drills focusing on the back kick each day of the week.
This is the idea behind doing dynamic forms instead of static forms. With static forms, it quickly gets into the territory where people just have too many forms. I heard it said by different higher-level folks at my old dojang (i.e. 2nd and 3rd dan) things like, "I can either learn new forms or I can improve the ones I already know, I can't do both," or, "I'm tired of learning forms, I want to learn application." This is kind of like the problem that BJJ beginners have, in that there's so much breadth to cover in the art.
This is to take the move-of-the-day approach and apply it to forms, in such a way that folks don't need to remember a dozen or more forms, but can still learn the techniques and concepts behind them.
One of my fellow students at my old school had a saying, "Good is the enemy of great." The idea that if you're complacent with doing a good job, you'll never do a great job.
Going back to BJJ, there are a variety of ways that BJJ teaches. Some schools try and have a curriculum, where at each stripe of white belt you learn XYZ. Most I think follow the move-of-the-day approach I mentioned above. More recently, some schools have started training the ecological method, which is where instead of drilling, you just basically do a bunch of games designed to teach a certain concept (i.e. top person can't use their hands and has to maintain pressure, which teaches how to manage your weight and balance).
I personally prefer a hybrid of the "traditional" move-of-the-day style and the "modern" ecological approach. I feel some drills on each side is better than going all-in on one of the methods. If BJJ guys had simply gone, "eh, move-of-the-day is good enough", we never would have gotten the ecological training.
Similarly, I can look at the Taegeuks, or I can look at the forms I've created and say, "eh, they're good enough." But then I'm teaching something that's just "good enough", and can I really take pride in that?
I am sorry you had such a bad TKD experience, it is not the norm.