People should have the right to die if they're mentally competent to make that decision. There is usually a legal document required for a "do not revive" order. I don't know why there isn't one in this case, or whether or not one is even required in that state.
There isn't one in this case because she went under 15 years ago, well before living wills became more common. She was young and the doctors did not diagnose the condition which eventually sent her into the coma(hence the malpractice suit). The living will in writing is not required - what her husband and others testified to was that she said orally that she would want to die.

The only question here should be what the woman wanted, not the morality or immorality of letting someone die.
Exactly! And that's exactly what the courts considered and ruled on.