It may not be an evolutionary flaw, but one thing that I can think of is the attaching place of the sternocleidomastoideu. If it were attached to the front side of the head (i.e. it didn’t cross the spine), muscles in the back of the neck like the trapezius could be effective antagonistic muscles to it. If so, the head would be automatically supported by the muscles in the back like the trapezius the same as the torso and the leg part. We wouldn’t probably have to think of our head to support it so much. (though we may lose the range of turning motion of the head a little.) Anyway, it isn’t so. It is still like four-footed animals. They need to pull the head back to see forward and to look around for foods or enemies by turning their head a lot, though we don’t have to do it so much especially in modern society. The support mechanism of our head are not adopted well in the current use. It doesn’t gurantee an effective condition. Therefore, we need to keep our head voluntarily or consciously. FM has realized it at first.
I think that “advantageous intention” in my word is another expression of FM’s direction. We move voluntarily because of our muscles. The electoric impulse in the nervous system is the ignition to contract muscles. Our direction or intention gets involved to give adequate electoric impulse (adequate level and duration, adequate target muscles). That is, what we think makes difference in terms of our use of the body. I am saying that there are advantageous intention for human being to use the body. Somehow, FM has found the ones which work adequately. I like the word “intention” because I can use it in wide variety of subject, even though I also use the word “direction”.
We are able to make up for our structural or functional flaws by our intelligence. We, human being, have ability to be aware of the self and to change our habitual use. No other species can do like us. So, what those who practice the AT is doing is to fully utilize this human ability. That is my understanding.