If a user's group settings are set to receive E-mails for "Only My Requests" they will not get an email notification when an admin is requesting on behalf of them. They need their setting to be set to "All Requests" which can get confusing. If requesting on behalf of someone, they should get an email no matter what their group email settings are.
@Dan Grassel Thoughts on this update - I think this makes a lot of sense, especially with all of the work we have done recently with the create user.