Yes it is because all you have to do is basically fake the frame of mind you were in. They really don't do the required Psychological Profile immediately after the crime has been committed they do it months to years later. If they saw the frame of mind someone was in immediately following the crime it would give a better picture of what the person was thinking. You wouldn't fake it right after it happens, but when you are sitting in a cell you can sit there and come up with all types of crazy things to say.
The insanity defense is so easy to qualify for that a majority of people being convicted of crimes pleas insanity, knowing that if the judge agrees and they put a good enough show on that they will most likely be let off without any jail time, as long as they are good at acting.
Yes, it is too easy to qualify for an insanity defense, because that is what everyone pleads who does not want to be responsible for their actions. The Mom of the autistic girl in Michigan is the worst offender. She is arguing that she should be found not guilty for her child's murder because she couldn't take having an autistic child anymore, and that is someone an insanity defense.
I do not believe it is easy to qualify for an insanity defense, but I question why this even makes a difference. In my opinion those that are insane still committed the crime and it shouldn't matter when it is time to receive a sentence. Insanity is an interesting defense to me because it has nothing to do with real innocence.