" So it's troubling to think that a game like Mass Effect or Dragon Age gives young players the idea that nobody will ever treat them differently once they find out they're anything other than straight, rather than give them the tools with which they can start to understand and accept the discrimination they may end up facing in their lives."
I understand what the writer is saying here and it is valid. As a counter point though, I think there are a lot of benefits to showing a completely normalized homosexual relationship (free of bigotry or even comment) to young players that are not gay. Not to say that games are role models, but that idealized fiction shows the flat equivalency of the relationships.
That idealization shows its transgression by being so divorced from the unfortunate reality.
Also, if aliens from another planet show up and bring hyperspace technology to earth--as is the lore of Mass Effect--I really don't think humanity would care all that much anymore about skin color or gay people.