I heartily second that request!  We have the same issue in keeping the groups display names in sync the names on file with a separate membership-only website.  We use "direct add" for all new members to set the initial display name, but as mentioned above, some people unknowing make changes.  We use the activity log regularly to check on changes, then we send them a note and change it back.  Having a no-change option, at least for us, would be very helpful.

Peace,
Tom