If you do not have a profile photo. You may want people to see your inner beauty, not judge you on the basis of a few computer pixels. Not only are we a visual species, we are also a cautious species. This will mean that people want to see your face in order to trust that your profile is genuine.

Or your profile photo is not good enough to show the handsome/beautiful energetic man/woman?!

Image is not just about appearance; it's introspective.