There seems to be a misunderstanding that a lot of people have. "Realism" has nothing to do with magic, it has everything to do with the role the world portrays. When you've got a magical universe which pixies can turn people into unicorns, you've got to accept this universe because it exists and the world explains to us that it exists. A dragon's existence in the world of Thedas is realistic in the context of the universe, as does the use of magic and the Darkspawn and what say you.
However, sexuality in the Dragon Age has been portrayed in a very normal way. Women and men procreate, sexuality exists and gender expectations exist. To believe that everyone the player encounters has flexible sexuality which bends in the direction which the player fits destroys said world, the fact remains that some Thedosian people--just like real life--are gay, straight and bisexual.
To mock the "realism" shows ignorance of what someone means when talking about realism and serves little purpose.