We created a few User custom fields in the Portal Settings.
We use these custom fields a bit less than the default user fields but we still use them often. And we would like to see the history of changes on these fields, the same way we see the history of changes for the default user fields.
Because all our user creation is done automatically, info coming for our Master data hub, it would make it easier to detect glitches in our synchro process of users if we could see the history on custom fields.