Yeah, good idea, humans only differentiate by skin color. Have you ever wondered why there is only one female smurf? It's because of sexism. And why aren't there any gay smurfs (smurves)? Why no smurves in wheelchairs? No autistic smurves or smurves with Down Syndrome? Sounds like eugenics to me...

Then some of the dye would wear off leading to light blue vs dark blue colourism.

No, it wouldn't, because racial differences encompass a whole lot more that skin color.

it's called tattooing. ;)

Plus people are dyeing the whites of their eyes as well now.

Will this start to affect the anal- bleaching fad? " And what colour would you like today, Madam/Sir ?"

We'll end up looking like a bowl of Smarties.