Why are the villains so over the top in the Dirty Harry movies?

A lot of people like Scorpio as a villain. The movie is pretty good, but I find him to be just okay, or decent. I think the problem is, is that Andy Robinson, kind of takes him over the top.

I noticed this with other villains, is that they try to make them too much like Robinson's performance. They are all wide eyed like him as well. Bobby Maxwell from The Enforcer is also over the top and wide eyed, same with Mick in Sudden Impact.

And the Dead Pool killer in The Dead Pool performed his character like that as well.

The only villains who are actually acted better, and are more different are all the villains in Magnum Force, and Jennifer Spencer is Sudden Impact. I like them as villains more because of this generally.

What do you think?