The point is, before this ruling, your fate was up to a jury of your peers, and the relative skill of your attorney. Now, your fate depends on the judgement of a court appointed psychologist, who may or may not be gullible, may or may not be willing to game the system to avoid signing someone's death warrant. May or may not be willing to stand up to accusations of bias or heartlessness.
In fact, where do you go to find a psychologist who is willing to sign a death warrant?