The Big Quest(ion)

Rock, Paper, Shotgun has kicked up an analysis of the side quests we're typically given during role-playing games, and how they could be improved upon if developers allow them to have a real impact on the game world. Mass Effect, Star Wars: Knights of the Old Republic, and Deus Ex are all specifically referenced, though the text is much broader in scope:
But I don't want my choices to always be life or death. And equally, I don't want them to always be wrong or right. Sometimes these are perfect themes, but not always. I want to fathom a means to create a sense of scale behind my actions, without their being so dramatically thudding. I want subtlety, but impact.

I think the problem is, too often, that your choice is reduced to a binary switch, and whichever way you flick it, nothing changes. Return to the island/planet/space station, and the consequences of your actions are sat there, lifeless, whether they're a corpse or a reunited mother and son. Talk to them and they might say, (Thank you so much for your help! Without my child would have died!) Return weeks later and they might say, (Thank you so much for your help! Without my child would have died!) The moment I was finished with them, they ceased to live. Their moment of reuniting happiness becomes something of a grotesque parody. Trapped in that instance, unable to move on with their lives, I might just as well have killed them both and robbed from their cupboards.

When I say (nothing changes), that's not strictly true. My experience changed, my memories of the events are constructed uniquely, and even though their existences are frozen in time, they're how I left them. I'm not dismissing the impact of this at all. What I'm wondering is: can this get bigger without breaking a game?