Thanks Nikodemus, that really helps a lot. I wasn't aware that this can be configured, since it's not in the option dialog.
EDIT: Ha! Stupid me!

I found the xml you pasted in skillwindow.xml, which made me understand your comment in a sarcastic way, thinking it's already configurable.
I agree with Zan, color blindness comes in many variations and each would need different color settings to be suitable. However, maybe the default could still be adapted to the most common deficiency, since it really is not rare (as opposed to most other types of color blindness). A lot of people aren't even aware of their vision deficiency.
miadon, I think the bars are just fine, since they need horizontal space just like the skill name, giving quite optimal space usage. The pie charts would need more vertical space and it's not easy to arrange them in a way that would not be more wastful with space than the current implementation. (But while you're at it, you could question the entire system. Why are skills half-trainable anyway? That just leads to lots of clicks to train and a difficulty to see which bar is longer when the differences are smaller than one pixel.)