I'd support this request, and once such selection tickboxes are implemented (to allow bulk deletion as per this FR), I would suggest to add another "multi-action" feature: add/remove from group(s):
select multiple list entries, and then have a button (same as the "group assignment" dropdown in each row in "group managment > domains") to assign (or remove) the selected rows (i.e. domains) to (or from) one or more groups.
Edit: now opened an extended FR here.