I meditate regularly, but I think this type of exercise is misguided and betrays the body-denying/denigrating bias that can be often found in religious traditions world-wide. It encourages an ignorant attitude towards the body: instead of contemplating the miracles of the muscular system, see it as amorphous flesh. Amplify the spurious association of the skeleton with the malnourished body it resembles, instead of marveling at the ingenious way it serves it's (many) purposes, and so on.
I generally agree with you that a lot of lineages, particularly the Theravada derived ones here in the west, might go overboard with body denial practices. The meditations from the Satipatthana sutra are great, but I feel like you can get caught in trying to prove everything is suffering if you don’t have enough grounding in other parts of Buddhist teachings because of them. Like all of the sutras it can point you in a direction, but we shouldn’t be caught up in them.
Personally, in my meditation practice, it was completely transformed and deepened when I began a dedicated asana practice and focused on giving my body what it needs to be strong and in touch with what it is saying.
That's like saying you are not your car; while you're driving the distinction is less important than keeping between the lines and watching for pedestrians.
I am a Daoist like everyone else is a Gravitist. You all believe gravity because you feel it work and it was explained and named to you. You feel Daoism and Buddhism work as well but no one has explained to to you.