Nero is Romulan, which means he has blood based on Copper rather than Iron due to his Vulcan ancestry.
It makes sense that he'd have different pigmentation.
Seeing Kirk and Spock in Red, for a red-alert situation, and looking at the color of those uniforms, I can see why they went with the iBridge from a visual standpoint.
Everything is supposed to be newer, more vibrant, and the primary colored uniforms stand out under the bright lighting.
Also, when they go to Red Alert, it provides a good visual reminder with the character's lighting without altering the functionality of the Bridge as a whole.
Of all the things I've lost, I miss my mind the most.