I remember my first time on scuba when were made to go to our knees, myself and others had huge trouble staying our knees. I can see we're your coming from when you say the skills would be easier to learn once neutral. Better start practicing demonstrating these skills neural to then!!
This is one of the things that people who are used to teaching on the knees do not realize--the skills are much easier to do when you are in horizontal trim than when you are upright, and kneeling is very hard to do for many people. Instructors argue that they don't have time to teach buoyancy in addition to the other skills--what they don't realize is that it takes less time because you are not teaching it in addition to the other skills, you are teaching it at the same time as you teach the other skills.