Why can't a moderator or owner be allowed modify member profile items?

Currently as owner or moderator I can do many things, but one that would be helpful would be to allow me to make changes to member profiles. Specifically, the ability to change a members email address and to add a name to the profile. Many members are changing email addresses frequently to avoid spam, but currently if they don't change the address themselves or if they simply don't know how to do it, they ask me to do this for them. Unfortunately, I have to delete their accounts and reinvite or re-add them in order to do this, but doing this changes their date joined information. Also, many create email accounts that have no relevance or attribution to who they are. Since my group is private, having the ability to simply add a last name would help us to keep track of who the addresses belong to so that we could delete orphaned accounts or departed members.