I thought about simply posting a modified version of my circular avatar fix, but saw a lot of gaps that needed to be closed up.
I probably won't be browsing the forums with avatars hidden (avatars help make users more recognizable and add more color to the forum), but I'm glad I could leave this fix here for anyone who wants to
Here is a companion userscript to fix an issue with no members displaying in some areas, such as "Birthdays" and "People You Follow". It will display them as usernames separated by commas. Unfortunately this issue can't be fixed with CSS unless those areas are made an exception to the avatar-hiding rule.