Ashtanga being my main practice style, I've always had a not so positive view of yin practice. Also, my joints tend to be more open, and I need to work stabilizing strength to counter that, so yin has usually not felt very good in my body. BUT I've been asked to sub for a yin class this Tuesday so I'm doing a little investigation... I really like your explanation here. The connective tissue theory I've read about is not very convincing... but to use yin as a lead in to a sitting practice makes more sense to me...