If people didn't want, or have to know why they (or someone else..say a criminal) act the way they do, there wouldn't BE any shrinks.  They serve a legitimate purpose, and many of our laws are based on criminalizing aberrant behavior that is unacceptable in society.  Do the mores of society change? Sure, and obvious aberrant behavior sometimes is "legitimized", if not as "normal", then "acceptable" to a society on a downward spiral.  What is "normal" is based on many factors, biology, culture, religion,  etc. among them.  Usually, it's just a matter of common sense.  
But, I think I'll go with a "court accepted" expert with decades of experience in dealing with those who aren't.  If someone else comes up with a more plausible reason for people who seek to destroy our Constitution, Rights, rule of law, family, etc.  I'll entertain their view as well!