I honestly think the greed will (and should now) be considered a mental illness.
At that point it would just be excusing bad behaviour, would it not? I wouldn't say putting it on the same level as mental illness is fair, either. People with mental illnesses don't want to be mentally ill. On the other hand, greed is a trait that directly shows itself in a person's decisions. You can choose to be greedy, you can't choose to have, say, arachnophobia.