There are probably things they could do that would have a bigger effect than the ad quality. But as long as those ads have some effect, and faces improve them,

There are probably things they could do that would have a bigger effect than the ad quality. But as long as those ads have some effect, and faces improve them, they'll keep doing it. Doctors and lawyers often put their faces in ads, too. It looks like people want to see the person they're buying a service from.