I'm not sure why someone need that tool. This is exporting user data outside forum. If we will consider it - It should definitly go into core admin user list, not for user directory extension.
If you need this kind of data for migration or other single use case - then going into MySQL database and build a query is a way to go imho.
I'm not sure if there is any separate discussion about core admin user list, so I will go ahead with this offtopic ideas - User Directory have options to sort users by last login date (which was taken out regarding to privacy concernes). I would re-introduce this funcion in core admin user list, as this can be usefull for administrators, to find out ghosts accounts with many months without logins, no posts etc. Ideally mass edit (to move them to different group or remove) would be amazing. I would love to see also other stats and filters (like number of posts, groups etc) in core admin user list.