My romantic choices in Mass Effect are fairly regular, despite what some of you may have assumed from the headline. My canon choice is the incredibly basic Fem Shep x Liara, while I've also cheated on Liara in Mass Effect 3 as Fem Shep with Trainor, and abstained the first Mass Effect before hooking up with Thane in Mass Effect 2 and saying a tragic goodbye to him in Mass Effect 3. I have even, while cursing Fox News, played as Bro Shep and romanced Ashley in the first game (I hit it and quit it by leaving her on Virmire), before finding my one true love, Jack, in the two sequels.
These are all fairly regular choices. The only ones not human are Liara and Thane, probably the two most humanoid aliens on the Normandy. Garrus is a bit much with his sharp mandibles, and I don't see the allure of the unknown with Tali. If I could get with Miranda as Fem Shep then I would have definitely cuddled up with the Corporate Mommy, but that only cements how basic my Mass Effect romance choices have always been. The desire for a geth romance doesn't come from, well, desire, but from an intellectual curiosity. Honest officer, I swear.
The geth are a sexless race, quite literally. They identify as a collective unit (we are Legion, for we are many), and share a hivemind. We occasionally see glimpses of individuality however, such as in the flashbacks to the start of the geth uprising in Tali's quest for her homeworld, and in the iconic question "does this unit have a soul?". It's this individuality that a romance could explore.
When Legion asks "does this unit have a soul?", what it means is 'am I more than a machine?'. We see Legion act heroically, ready to sacrifice itself for its people, but also for its crew, who have no real benefit to it or its hivemind. When Legion fights for you, it does so out of duty, loyalty, compassion. These are all human emotions. 'Does this unit have a soul?' is Mass Effect's version of 'Do Androids Dream of Electric Sheep?'. It is asking what makes an intelligent machine a true life form? There is no measure for what makes you alive, not when machines advance to a level of intelligence that makes them functionally identical to organic life. When Legion says 'does this unit have a soul?' it is asking 'can I fall in love?', and the next Mass Effect game needs to answer 'yes'.
There is the fairly major question of how this would happen. Even if we accept, following the events of Mass Effect 3, that the geth are not the evil faceless villains they are in the first game, it appears the next game will make the 'Destroy' ending canon - that means no geth. But then, does it? We've seen in the poster that geth do feature, even if our only confirmed sighting of the geth is one dead specimen and one huge geth-shaped crater. If we assume that even in the Destroy ending, the geth bodies survived (or at least some of them did), then couldn't they be resurrected? Tali's father's experiments on exactly that are the backdrop for her loyalty mission in Mass Effect 2, the pinnacle of the entire trilogy. If they can be resurrected, could they be separated from the hivemind? And would that, in turn, give them greater freedom to experience all the joys of the soul, including love? Also, if we get greater creative control of our story like in Dragon Age, we might not even be a human (maybe there will be no humans at all), and could yet get to weave a love story between a geth and a quarian.
I'm not even sure if I would pursue a geth romance myself. There would be a level of fascination that would pull me into seeing the narrative play out, though it probably wouldn't come from any real attraction on my behalf. Just as likely I'll be glad that it's there and end up romancing the pretty asari on my first playthrough, just as I did with Liara and Peebee. Mass Effect has previously used Yvonne Strahovski and Natalie Dormer as face models too, though Dormer was not a romance option. If the new Mass Effect game does that again with someone like Anya Taylor-Joy, then all the intellectual curiosity in the world could not stop me kissing ATJ in space.
Everyone always wants more from Mass Effect romances. They're some of the most developed in gaming, and that's why we're so eager to always add to them. More options, more queerness, more races. More, more, more. Mass Effect has more to it than just being a dating sim, but the relationships underpinning your character sit at the heart of every journey. The next game needs to go even bigger with them, and a geth romance could be the best way to do it.