Originally Posted by Zinc Saucier
I have no idea where it originated. I just remembered seeing it before so I did a Google Images search and found it easy enough.
He was also wearing a practical Mark VI in this scene even though on screen it was the Mark VII:
I'm guessing they just never built a practical version of the Mark VII since it would only really be needed for those two scenes. And having a practical version of the suit on set probably helps the animators with lighting and stuff even if it's the wrong suit.
Also, despite the big budget, Marvel's still quite the penny pincher. Why waste money on building something for which they were already building an incredibly sophisticated computer model that they could use in pretty much any shot they wanted? As you said, it would have only been for those two close-up scenes anyway.