Honestly, Gay options are relatively new, you must admit.
New-
ish.
In Star Ocean 2 (back in 1999), whichever character you chose (Claude or Rena), it was possible to build up your romance level and date one of your team members of the same sex.
In the Sims series since 1, you could have relationships with the same sex if you wanted to. They even allowed marriage to where they would both dress in groom/bride outfits (depending on their sex) when the time for marriage came.
Likewise, the Fable series has always allowed the player to choose the person they wanted to be in a relationship with, regardless of their sexuality. They're actually one of the first I recall that even introduced STDs into the mix if you didn't wear a condom when you went to have sex.
In the game Bully, the main character had a plethora of options to choose from when it came to the women, but there were options available for males to make out with if you wanted (though actual relationships were a different story). Down the road you could earn a skill that would make it so you didn't have to buy the women anything if you wanted to make out with them...however, it didn't apply to the guys (you'd always have to buy them something).
It's just in newer games it's become more...prominent. Though I feel like it's also become a bit constricting as well. Whereas in games like The Sims and Fable to where options are vast and practically endless for anyone (the sexuality of most NPCs in Fable since II change with each new game, and practically anyone can be swayed for either sex in the Sims, you can marry practically anyone in Skyrim and Dragon's Dogma)...games like Bully, Dragon Age, Mass Effect, and Fallout are restricted to list. Gay options exist, but the list is just a bit slimmer.