Today's ruling by the Supreme Court striking down the Defense of Marriage Act, or DOMA, is both ground-breaking and trivial at the same time. It's a huge change from a legal perspective, but more of a "duh!" moment in human progress.
We look back 40 years or so, and see the landmark cases that struck down laws against interracial marriage, and have a hard time imagining living in a world where you can't marry the person you love because of their skin color. From our perspective, those decisions were trivial: of course you should be able to marry someone regardless of their skin color or eye shape. That's just silly to think otherwise.
It is my sincere hope that 40 years from now, people will look back on this decision and have a similar "duh!" reaction to it.