Forfeiting the privacy in a third party is exactly what privacy stands for; selectively revealing your activity to the world. I don't care if I reveal my activity to some mixer, as long as I keep it private from the people I exchange bitcoin for, and from those that I spend it on.
If all you care about is keeping your Bitcoin private from the people you spend it with even if you forfeit control of your money and data then why don't you use a Bitcoin exchange instead of a mixer? You would get even more ""privacy"" since the user base of an exchange is larger.