Wasn't the original idea behind Growth to enable you to build Colossal Boy from the Legion?
The bigger you get, the stronger you are, more durable, move farther, etc...
I too would like to see a return of the old growth chart, but I wonder about disconnecting everything from it. To me, Champions I-IV was built with a normal human as the template or base, then if you were bigger it meant something or smaller it meant something different. They've gone away from those "absolutes" and I struggle with that fact...