It's a tacked on feature to profit from the popularity of Bioware's in-game social relations and to get the media buzz for including same-six marriage, as shallow as it may be in the game. Sadly, social interactions has never been Bethesda's forte.
and yet, every quest involves chit chat with epic charcaters. I know they can do this, they just have to want to. I know not everyone cares but a lot of us do -cmon Bethesda, give us some meat and potatoes to this aspect of the game in a DLC.