Here's an idea to add a personal touch to your community. I've created a custom HTML Widget to encourage users to complete their profiles with a snazzy avatar. Having custom photos/avatars help to bring out the personality of your community and encourage engagement. It's why give badges to users who upload their own photos.
This is a DIY widget that you will have to DIY (or you can DI with some help from someone from your team). It requires inserting a Custom HTML Widget in a Homepage Layout in the Appearance tab.
The idea is to detect if the current logged in user has a default avatar, and if so, show this message. If they have already uploaded a personal avatar or photo, don't show this message. It can look something like this, only cooler: