Terastas - That is an interesting idea.
You should know, however, that the original statement isn't really my idea, it's almost a direct quote from Nietzche's "Geneology of Morals".
I can't finish the quote perfectly, but the reason I buy it, and the reason I say cruelty specifically, is that I am thinking of cruelty in a very physical and material sense. While flaunting an offensive opinion can be fun (I occaisionally enjoy wearing a Baphomet medallion, for example, though I doubt anybody recognizes it) and could sometimes be considered cruelty, I was thinking more of illegal cruelties.
The basic arguement goes that the real reason we have laws is so that certain levels of cruelty are illegal. An example: While nearly everybody has wanted to kill somebody at some point, almost nobody would like to be killed themselves. The fear of cruelty being inflicted upon one's self typically outweighs the desire to be cruel, so we have agreed (a la the Social Contract theory) that nobody is allowed to be that cruel.
The "evidence" cited includes ancient laws which would be considered cruel and unusual punishment, such as "eye for an eye", or, as the Romans called it, Lex Talionis (Let the punishment fit the crime). This certainly doesn't prove the theory, but then, philosophical views rarely can be proven. I have thought about it and it seems to fit.
I understand that you are not disagreeing with me, and I thank you for the reply. I just thought you might want alittle background, since the statement itself is admittedly shocking and "out there" from the mainstream.