Thanks for the comment, and I agree with you. I didn't paint them intially, but in the end decided to, because:
I was trying to keep the toys somewhat robust, so that I can still play with it like a toy. Therefore, there are areas that I don't want to paint over, because it will scratch up in transformation, (like the pale red on the upper and lower leg). This must have been my biggest challenge in pulling off the black/yellow focker scheme.
So in the end I have to paint the missle head to bring out the yellow, use black "no step and caution" decals to re-enforce the black. Lastly, the few red decals here and there are to balance out the red, so that it is not concentrated in one spot in fighter or battriod mode.