i am with you 100% on this! i am about to embark on leading a yoga teacher training through my yoga school Modern Mystic Yoga Academy and i will be emphasizing the 1st two limbs of yoga immensely. They are the secret power behind the reaching the later stages of meditation, for how can one really remain in stillness with a head full of regret or shame?
In the west, i agree that people are obsessed on the physical and outer appearances, but i imagine in time they will crave more...hopefully. Especially, when they have done every pose and realized that it didn't make a difference and that they aren't any more enlightened, necessarily. But maybe through doing the poses, the winds (prana) will shift in their bodies and they will feel inspired to study all the limbs in order to catch their minds up to the physical transformation they are experiencing.
It's going to be a hard sell to promote morality, for by preaching principles in general one doesn't usually win the popularity contest.
That is why i say, that true yoga isn't mainstream.