Khayness wrote...
Seeng that your scars heal if you are paragon and your face falls apart if you are renegade (sorry, but I don't accept Chakwas' mind over matter explanation), why would you assume such a complex thing with awesome ideas behind it?
I think this is just another "Boohoo, I want a halo over my head or horns to show my alignment!" thing. Done by wizards.
I'm guessing it is just symbolism for Sheppard's final decision. The color is churning a bubbling throughout the entire game, but at the end it changes into a solid color.
destroy the base = blue, save the base = red.
So, I agree with Khayness, it is just a way to show your alignment.
As to why? Maybe the Illusive Man likes the backdrop. Or, maybe he has a chip planted in Sheppard's head that reflects his alignment to a giant animated star behind him... just for kicks. See, it wasn't rebuilding Shep that cost so much, it was the darn disco star-ball!