Personally I think it depends on the type of game and the type of investment you may have in your character.

For example if it's a linear, developer narrative driven game where the protagonist or one of the central characters is gay then that would have a different effect to let’s say an RPG where you create your own character and their back-story i.e. Mass Effect.

I think it would be interesting to play as a gay protagonist or having gay characters in a game however if it came down to a create a character RPG style system I wouldn't necessarily choose to create a gay character, solely for the reason that when I play RPG’s I tend to base the character loosely on myself and as heterosexual that doesn’t fit my modus operandi.

I've increasingly been reading The Border House Blog, and I think that if we're to examine videogames through a critical theory lens, then these things absolutely do matter. Unfortunately, so few developers actually consider the consequences of the imagery they employ in their games, not to mention that the sheer number of games that feature over-the-top heterosexual masculinity kind of overshadow the number that take gender questions seriously. That's endemic to most media forms anyways, but it seems much more pronounced in videogames for whatever reason.

Games are still largely being made by people for whom Aliens is the beginning and end of film, and for whom Dragonlance is literature.  Games don't stand up to criticism, because they are not being made by literate people. 

I'm obviously making an enormous generalization that is not true across the board.  There are a lot of people involved in making games who would love to put more of an investment into the emotional lives of their characters.  The way games are cobbled together makes this incredibly difficult, even if the team means well.  The unfortunate thing is that most of the time it doesn't even seem to be a priority.  

Of course, we're all word nerds, so naturally we think writing is of great importance, right?  

I'd love to see a greater variety of people represented in games, but for someone's sexuality to matter, you have to care about them on a personal level.  Nobody cares about Dom's wife, so they're certainly not going to care about Carmine's sexual preferences.  (That's a reference to the Gears of War series, in case you're not familiar.  In the second game, they tried to delve into the characters a bit more and failed miserably, because the writing was still utterly immature garbage.)

As long as I'm engaging in wishful thinking, I'd like to see black characters who aren't stereotypes, I'd like to see women who aren't sex symbols, and I'd like to see protagonists who aren't idiots.  

I should point out that for all the negativity in this post, I am optimistic.  I think we'll get there.