What about all the other states that anticipated this cultural battle and passed laws refusing to recognize any such marriages? The coming dispute among states will go to the Supreme Court, and even if the next three appointees are Scalia clones, I'll bet the court will hold that the laws of one state that do not offend the U.S. Constitution must be recognized by all other states.
So this amendment is needed.
I agree with Safire. The language of Lawrence digs the trenches for the assault on marriage as certainly as the Anschluss augured WWII. DMA is now the marial Maginot line, and will not withstand Lawrence.