In reply to Justin Tadlock.

Having authored a popular User Profile Picture plugin, core would have to do a few things:

Add a way to change your profile picture besides Gravatar.
Add a way to add social networks in a user-friendly way.

I have done both with plugins and have even come up with my own author box blocks in a separate soon-to-be-released plugin.

Core would have to dive deep in order to make this a good user experience.