Banned User not being removed from Groups

When a user is banned they are only removed from system groups (except Banned Users group) but aren't removed from custom created groups. Is this intentional behaviour?

If so, is it possible to add options in Admin to select whether to remove from all groups or to have a list of groups to remove from on ban?

Currently I'm using the ban action hook to remove from custom groups but it doesnt allow the Community Managers to manage that list if and when they add a new group.