As I mentioned, emailing users is part of managing users.
If you think things should be separated or there should be additional admin permissions, I'd recommend posting them in suggestions as other people may have their own ideas.
I still believe this is definitely a bug. If I only choose "Manage Bans" when adding an admin. I expect it to allow only managing bans. I don't want them to rebuild caches.
Ok. I'll post the email users issue as a suggestion.