I actually really liked the egg as an icon, and I'm sad to see it go. The colors should have been rethought though. Muted colors that are universal for all accounts (instead of each account getting its own bright color) would also encourage users to upload their own photos.

I don't see the point of using an "alternative" head shape, or including shoulders in the default image. No matter how the head is shaped, it'll represent some users more than others. Using an egg avoided this issue of approximating a human shape.