That may be true, but wasn't it also true before every major advancement liberty and equality under the law was made? You can start at the Magna Carta and move forward in time and see the advancements in the ideals we espouse. And at any point if someone had said "Well, this is more than we've ever had" then no more advances would be made.I agree, but in many ways, the United States today are closer to living up to their ideals than they have every been.
Instead, good men and women stood up, protested, went to war, were maimed and died, passed laws, and everything else that got us here to where we are.
So, are we to be the generation that sits on our laurels and says, "Well, that's close enough"?
Others before us were better than that.
We should be as well.