Thoughts On Iron Man, Spiderman, And ILM

I saw the trailer for Iron Man recently, and I have to say it reminds me of the recent Spiderman movies. By that I mean I'm seeing the same stilted motions in the CGI characters. ILM did the work on all the films, from what I gather, but they also did the work in the Star Wars prequils. The stormtroopers were completely convincing, even with so many of them on screen at once. If I hadn't heard otherwise I would have thought at least some were live actors. But both Spiderman and now Iron Man look like they're computer generated. There is never a moment's doubt watching them. Why is this?

I can think of three possible explanations...

A: ILM is perfectly capable of producing convincing animation of human characters, but only does so for Lucas.

B: ILM is perfectly capable of producing convincing animation of human characters, but will only give their clients what they're willing to pay for, and Sony and Marvel were only willing to pay so much.

C: ILM is perfectly capable of producing convincing animation of human characters, but only if basing them on the movements of a living model. They had live actor stormtroopers from the original Star Wars trilogy to work from, but for the Marvel superheroes only had still images from comic books. And let's face it: those comic book drawings evoke some very dramatic motion, but they are not realistic poses by any stretch of the imagination.

So what do you think? Is it A, B, C, or something else?