No, no they're not legit at all. They're complaints made by obsessive whiny little babies.
My phone has a slight yellow tint but I don't give a damn. Why? Because I use it, I don't obsess over the shading of the screen.
It doesn't make you a whiny baby to not want a yellow tint. I'll say it again, its a $650 piece of equipment.
Don't give me this "i'm privileged" garbage. If OP returns his bumper, the money doesn't go to the less fortunate, it goes into the $76 billion dollars apple has. Apple has already accounted for that loss.