The problem is that you have no context or perspective on the model you've seen a static image of.
1) Standing next to the full-sized, animated model will give you a very different perspective when you're looking up from his toenail
2) Knowing that he will only come out of his lava pool to reveal his full figure in a Heroic-only phase of the fight will give you a bit more context
He's not just going to be running around the moment every raid reaches him.
I don’t think a lot of you understand; perspective is a large part of art design. The designers probably designed the model looking upwards from his feet. I bet you Rags’ll look epic when you see him in person
This is sort of what I was getting at with my first point. The perspective is completely different when a player character is standing near him. The proportions were designed with that in mind, which is why the screenshot of the model really doesn't do Ragnaros justice at all. (
Source)