I bet you anything that there was a time when you're coach told you all the same things about inside leg, outside rein, shoulders, positioning, blah blah blah - and that at the time you were going wth am I supposed to do with all of this information - LOL... it's so easy to say "simplify" when you already have the ability to do it, and do it beautifully! I agree with your line of thinking, I'm just saying - remember back to when you weren't the gorgeous rider that you are now and you were going through the same issues I'm having, and try to remember how that felt.
This is why it is important for coaches of all types to have training in how to coach people and how people learn. Our horses learn a lot faster because they know how to walk trot and canter naturally. For humans it is not in their nature to be sitting on a horse and instructing it. This is why most of the training should be focused on the rider positioning herself in the most opportune place to allow the horse to do these things. The horse can already to P & P, go round in a frame and swing over the back naturally - we do not have to train them to do this. As riders we have to only balance ourselves to allow this to happen. This is what I think is a flaw in your thinking.
As far as for teaching people we need to only be giving them one bite of information at a time. Most coaches want to see the riders progress as fast as possible and be able to put the pieces together quickly. This is because they can do it and they find it easy. So they get frustrated and pile more things on the "To Do" list when the rider is simply not ready.
As riders, we need to simplify. Focus on the most important aspects first, and the least important aspects later. There is a saying, 80% of the job can be done with 20% of the work and the final 20% will take 80% of the work. We need to get the first 80% dealt with and then chip away at the final 20%. This is why I am saying - focus on what you can control. Get your balance, get your seat, stay centered, don't hang on the rein or over complicate things for the horse. Use your legs to go forward, your seat to balance the horse.
You can't just hop on and expect to get your "To Do" list done every ride. Start at the top - this is the same thing I do every ride. Get your head in the game, get yourself figured out and then start chipping away at the details. Some days I don't make it out of my warm up phase and that is OK! As long as I don't get frustrated, keep it simple and then I will learn.