I know I missed a few, but you'll have to back up your point if you want it to stay.
Good thing for me you haven't really touched my point, which is that of the actual
advanced techniques, that is the ones that only show in the play of the most dedicated smashers, the ones that require hours in Training mode developing the muscle memory to utilize consistently, the vast majority will be unintentional.
You've covered a lot of the most basic of the so-called "advanced techniques," which are only included because they aren't available in the original documentation. Most of these require no actual practice to utilize, like fast-falling, or jumping out of shield. Shield-grabbing is actually not an advanced technique, seeing as how anyone can put two and two together from the HtP video's advice to press A and the
shield button to grab.
The problem is, while most of these are intentional, they're also easier than picking your nose, because the designers could dictate their difficulty. In fact, I don't think I go too far in saying that L-cancelling is the most difficult intentional technique in the game, and it's only so hard.
Let's look at a technique that was not intentional: wavedashing. This move requires that you time your airdodge at the very moment you leave the ground, otherwise it loses effectiveness. Furthermore, to have full control of the wavedash, you need to be able to distinguish between all of the angles and their correlating WD distances. This takes training. You need to teach your muscles how to do the motions reflexively. This is what I'm talking about when I made my point. This technique was very definitely not intentional, and thus the designers couldn't dictate its difficulty. This is why it's considered hard.
I could pick something more obscure, but suffice to say, they only get harder.
So the Advanced Techniques that the designers can dictate the difficulty of can't be any easier, because they're easy already, and the unintentional ones whose difficulty is out of their hands obviously cannot be made any easier.