Nice thought out post!
I was never saying horses don't feel it and react in someway. They can feel a fly land on them and move indivual spots to shoo it off so they are extremely sensative to feel. Im saying that yes EQ matters a lot, if my horse is doing a choppy trot and cantering on teh wrong lead etc I will look at how my posture is compared to her body.
Example, Chance was really cutting the corner and falling in on teh circe and I figured out that it was because I was leaning more to the inside then I should have. Once I put my body where it needed to be she rounded herself and did it nicely!
So yes it matters BUT! Its good to have relaxed rides once in a while. My horse knows when Im coming off balence or w.e she will do what she can to get me back under her.. and it doesnt scare her or anything. I've ridden horses that if you put you leg one CM more forward then it should be the horse would just act up and not behave, and that's ridiculous. My horse can do whats asked of her even if im totally leaning back or just messing around, its harder but she's fine when doing so and she doesnt mind.
Im giving her a few days off from riding but once I get back on her were going to be doing a lot of work on getting her to put her hind into use and work correctly.
I've been doing a lot of reading and trying to learn as much as I can.