Well, considering that the Thing is 6 feet tall, and shorter than Mr. Fantastic, I don't see how any of this applies. And the Hulk and the Juggernaut aren't much larger. They are powerful beings, not giants. Going back to my point, the key is in knowing how to film, frame and light the characters to give them a more imposing presence.
As far as Juggy, he wasn't fully depicted because he was in a film that made him an idiot henchman, instead of someone who could take on the entire team of X-men, or Magneto himself (Being that his armor is magical, Magento would have no control over it).
Regarding the Hulk, If anything, in the movie, the Hulk's size took away from him, because he looked, for all his height and girth, weaker than he is in the comics.
The key is not to lean on CG as a crutch, but to make it a tool.