Yup, in the privacy of your own home, it's another matter, Yahoo etc target ads based on your browsing history etc, which is, to a certain degree, at least a bit more of an accurate way of deciding your tastes/nature than some kind of 20th century version of Physiognomy.
Thing is, if I chose to install something that allowed my Webcam to 'recognize' me, that would be my own choice to install, it could, for example, be another level of security, a biometric password, kind of, and I could remove it if got on my nerves, but to have not only the act of recognition forced upon me, but also allowing algorithms to decide what is best for me as a consumer is scary to say the least
