Your coach could have told you and it is very easy to understand if you take the analogy of the "short push" practice.
The practice is you stand in the neutral position, the coach plays a very short serve and you step into the table with your right leg under the table to get closer and you push short or flip.
If you would just stay like that with the right leg under the table already bending over the table the coach (if he is a proper one), would tell you to go back to the neutral position before he played the next ball, because the movement from neutral position to close to the table with the right leg under the table is a very important part of the whole move/stroke.
Now try to do the thought transfer.
If you stay upright/tall on those smashes because you know the next ball will come high you are missing the crucial transition from neutral position to the smash/kill position and you will make lateral movements while standing tall instead of moving like you are supposed to.
Don't get me wrong, footwork is probably also the thing i have the most potential to improve upon (that is a nice way of saying my footwork is shit), because it is super important for table tennis. My coach estimates footwork to be at least 70% of table tennis. He always says "If your legs dont make it to the right position, your hand will not stand a chance to make up for it". We are talking about players that played 1. Bundesliga in Germany, so perhaps they know a thing or two about the sport.
I have not even had a 10th of your coaching lessons, but i know that these are the things my coach would tell me to take care of so it is easy for me to spot in others.
You are pretty judging for somebody just a few weeks ago crying about not being taken seriously even though nobody saw how you actually played (which we are all still very keen to see you perform against those long-term players that you beat).
In this case, sorry, but you have no clue, if you think executing the strokes from the neutral position is stupid, because you already know how the ball comes in a drill.
how dare you imply i had no clue even though you never saw me play or do a drill ?
But let's leave it that way. You think you have it all figured out and your non polite cocky way of putting others down comes from the illusion that you are a very unique talent, but tbh what i can see in the drills you posted the level of technique i see is exactly what i would expect if somebody played that much table tennis and got that much coaching.
You are not that special. I have seen people with more table tennis experience have worse technique definitely, but i also know players with less coaching but better technique and skill after 2 years.