Yes, God said that it amplified what was already there, which makes the question why the heck did he trust Lucifer with it? However, I will argue that many people are jealous of/don't like their siblings, but don't actively work to corrupt, destroy and kill them. Without the Mark, Lucifer would have stayed a self centered jealous jerk, but would he have taken the actively evil role that he did without it? I'm not sure he would have.

Basically, God gave Lucifer a substance that amped up his anger and encouraged dark thinking and actions. Lucifer needs to be held accountable,and probably needs to be kept away from people and the world, but it's the one true argument that helps excuse or at least explain his worst actions.