Use an identicon as the default user image

Having an option to replace the default user image (whenever it is used) with an automatically generated Identicon based on the User ID would be a helpful way to keep track of certain individuals who not only delete their profile images, but change their usernames, quite often. It can also help serve as an anti-spoofing measure, and there could also be an option to show it based on IP address instead of account ID, in the case of alt accounts. Not to mention, they're pretty.

My reason for making my proposed feature optional is two-fold:
1. Somebody might actually prefer the existing default icon.
2. This could potentially reveal sensitive information in Streamer-mode or while taking screenshots.

Clarification:
I am specifically referring to this variety of Identicon:
https://upload.wikimedia.org/wikipedia/commons/d/d1/Identicon.svg
Not the Pixel-monster-thingamajigger kind that was popularized by Gravatar. I hate those ones.