This is really a cultural issue. In the US, pictures are a big no-no but in my experience with LATAM and European companies, pictures are common if not expected.
Design wise, the picture is a good opportunity for visual appeal.
Picture on resume is not mandatory. Users always can just to leave picture field blank and on resume it will shows default dummy/universal photo for all genders.
I don't think anyone would want a placeholder in their resume, but I agree that this being an online version, not having a picture is mostly an annoyance (you can easily find someones picture online).
Cultural point maybe. I know that I want resumes I receive to have a picture: much easier for me after an interview to remember who was who if I have a photo to remind me.
Why? Those are online resumes. Why they cannot be with pictures. These online resumes are for online presence. There is also print version of each resume.
Even for average guys, the picture is a welcome visual element in resumes. US-centric resumes tend to be very wall-of-texty because of the "ALL RESUMES SHOULD BE X PAGES LONG" (X in {1,2}) policy forbidding the use of "wasteful" whitespace.
Design wise, the picture is a good opportunity for visual appeal.