I just tested this in both C5 and C6. The scaling behavior in the Vertex Modeler is identical as far as I can see, unless I'm not understanding you. You have to grab the small tan colored squares that are present on each side of the bounding box to resize (pull) the desired side.

The behavior of Scale in the Assembly room is a different story. In order to get the same results as in C5, you have to go to the Motion tab and under the Transform heading, change the Lock from "Hot Point and Center" to "Hot Point Only". Unfortunately it doesn't default to that setting so it's an inconvenient  PITA.