Hi Psygorn, some info on control points in the FAQ here:
http://moi3d.com/faq#Q:_Why_does_show_points_work_for_some_objects_but_not_others.3F

A box is a special case where every edge in it is a natural edge of the underlying surface and that's why you can see points on it. When an object has a joined edge that is not a natural edge of the underlying surface then that's when you won't be able to show points since if you moved some points you would pull open a hole in what is supposed to be a joined edge. To turn on points in that case you need to use Edit > Separate to break pieces out into individual surfaces. You can always show control points for a single surface that is not joined to anything.

- Michael