First off, whether or not moral behavior is a "limitation on humanity" in the first place is rather subjective. What you seem to view as "evolution," I view as devolution into ever greater depths of callous selfishness and animalistic depravity.
Secondly, as I already pointed out, European culture has always been rather morally lax in comparison to the American variety, even when the Continent had extremely "Conservative" political institutions in place, like state religions, monarchs, limits on speech, and unlimited state powers. As a matter of fact, in many regards, Europe remains less "Liberal" than the United States where such issues are concerned to this very day ('Hate Speech' laws, extraordinarily stringent economic regulations, an almost complete lack of ability for common citizens to bear arms, etca, etca).
You're implying a connection here which simply doesn't exist, I'm afraid.