Ambivalent on the topic. It was rather pointless roleplaying back in XI, and I don't see that changing much for ARR.
So I suppose in that case, I find same sex marriage with other players to be a non issue. After all, looking at the demographic, there's an absurdly high probability it's two dudes in real life getting their female avatars to hook up, which is some kind of double gay, gay squared, if you will. If the media picks up on that, as they say, any publicity is good publicity.
But it really should be an afterthought at best. Making sure the game isn't a mismatched pile of garbage like it was at release is a bit more important, along with job balances, releasing content to keep people with multiple 50s from complaining about a self-inflicted drought, PvP, Companions, and the myriad of other things most would agree are more important.