There are allot of ways that a company can monetize their employees and allot of factors that end up being calculated to come up with the figure they end up paying for them, being socially well adjusted and attractive can have a good effect on your salary as people both tend to equate intelligence to good looks oddly enough and that they could use you for other things as well.

In some cases it also might be ticking a box kind of thing I've seen companies recruit attractive females before to both tick the diversity box and to keep some of the more social awkward coders working harder (this came directly from the mouth of a female headhunter that even boasted she specializes in hiring office eye candy that can do some coding on the side).