I think we have to be careful tossing the word "moral" around. Most laws are based on some kind of morality. What it comes down to is what the majority wants to allow and not allow, decided by the democratic process. How many people do you know that want murder to be legal? The problems we are seeing now are caused by a certain minority gaining enough political power to force their morality on to the majority. And even there it's easy to find examples where the minority has been shown to be right, or at least to have won. Slavery is an example.
Yes, slavery is an example of what can happen by allowing the government to enforce moral ideals.
Myself, I'm a moral relativist. While I might agree with you on morals, I respect the right of folks to think differently from myself. However lets try to limit government enforcement just in case those folks thinking differently get into power.