They've had blurred faces for as long as I've been checking their site, which has probably been 3 or 4 years now. Most of those girls don't do this as their primary job, and blurring out faces is pretty common or standard just about everywhere you go worldwide.
As much as I agree that "I want to see what I'm paying for", especially since cute/attractive faces are a big part of the experience for me, I'd much rather know that the pictures are actually of the girl, are fairly accurate, and her measurements are accurate.
I know that with AM, the pictures are of the girl, and for the most part I haven't ever been disappointed with the girl they've sent. They don't exactly staff drop dead gorgeous girls, either, but they've all been above average.
You can contrast this with a number of Tokyo sites where they do show the girl's face, like:
http://www.dh-salvator.com/
100% of the pictures of girls on that site are taken from various internet models, and don't belong to the girls. I'm actually suspicious when an agency does show faces -- but google image search usually exposes them.
With AM, they are a good enough org to say "hey, I'm looking for X, can you make some recommendations?", and they'll try to fulfill your needs if they are able to.