There are issues that I could see varying state by state. For instance, I might reasonably expect different laws regarding fireworks in Nevada than in Minnesota, because of the differences in climate. However, I can’t understand the justification for basic personal issues such as gay marriage, abortion, etc. being any different in one state than another.
My mother, who is an attorney, says it’s because “Family Law” is traditionally determined by the states.
I still don’t see why such things should vary from state to state.