The obvious problem there, someone gets married in one state, then moves to another. Or, like many people, a married couple has a spouse working in two different states.That is a problem for heterosexuals who make up the vast majority of people. Gays are a small minority that tends to congregate in certain areas. There's no "logistical" problem there. The courts can ignore homosexuals and life won't change one bit. Can't do that with heterosexuals.
I suspect the justices who were in favor of legalizing gay marriage did it out of a sense of fair mindedness.