if you ask me, Mars doesn't appear that uninhabitable at present. FWIW, I don't know if this is "false color", "real color", or "true color"...all I know it is the color produced by the MEX instrument. But the color is not the most intriguing aspect. See for yourselves.
Seriously, in Cosmos, Carl Sagan stated that if any planet had any kind of life, we should do nothing. Even if the life was simple microbes. Leave the planet to them.
I disagree. Terraforming would be to increase the chances of survival for the human race. While I agree that everything within reason should be done to protect any alien life, in this case we should look out for #1.