I agree with your main thesis that colour adds information.

But not with your reaction to colourblindness - it's surprisingly common. We changed a grid of clickable red/green squares to add crosses and ticks after a chance comment, and several more users bothered to contact us about how much easier it made the UI.

So please DO give a... fig... about colourblindness - if it's worth adding colour to help users, surely it's also worth a little thought about how to cater for colourblind people. In this case, a grey-scale palette perhaps?