Since the new raise/lower options appeared in the Group window context menu it seems like some other commands may be missing. UI authors can't make changes to the context menus or else I'd add some things including kick.
Years ago I used another custom UI that had buttons right on the top surface to kick group from raid, kick member from group, leave group, etc. When I started raid tanking I was constantly fumbling the buttons and kicking groups, or dropping out of the raid accidentally. In frustration I figured out how to remove those buttons from the raid window, and that's how DarqUI got its start.