Optimus Prime's move color scheme

This thread is not a rant on Optimus' movie paint job. IIRC, the reason given to fans for the "dark" rendering of Optimus was the difficulty in using red in CGI. At the time it was a believable statement. However, Iron Man has shown the fallacy of the assertion that red is more difficult and less believable in CGI. The special effects in Iron Man were spectacular. I thought they were better than Transformers--primarily because the action was not shakey and jittery. So what is the majority consensus on Prime's movie color scheme? It is already known the flames are a Bayism. What about the dark blue? Were Prime's colors really altered to make the CGI work more realistic?