When it comes to moral ambiguity, writers have to walk a very tight rope, because I've seen so many developers/writers fail at trying to present it. 

It always boils down to, something like...."well, this thing has good aspects but negative aspects as well." Which is fine, and it's realistic, but the level of the negative aspects cannot overtake the positive ones. 

[i]Fallout: New Vegas [/i]is a prime example of failed moral ambiguity. Obsidian tried to show us why Caesar's Legion is an equally viable choice to consider compared to the NCR, House, or the independent path, because they're stable (they aren't) and keep their lands in tight safety (from non-Legion memebers).

They're also a horrifically brutal society (fine with so far) that engage in slavery (you lost me) and what what I would call 'Institutionalized Rape' in order to breed children to become soldiers. I'm sorry, but when you have to resort to slavery, misogyny and rape to make your video game faction 'dark and gritty' and then attempt to tell me that they're actually just as valid as anyone else, I'm both disgusted and alienated. 
There are lines of taste that shouldn't be crossed. Slavery and misogyny cannot be used for good intentions. 

There are certain lines that are drawn, lines of taste. Having all of that in the game is one thing, but I won't abide by people telling me that it isn't evil. 

And don't even get me started on how it's handled in [i]Dragon Age[/i], ugh.

Moral ambiguity needs to stop being "both sides are wrong" and it needs to start being "both sides are right" 

'Would you rather have your hand cut off or your foot' vs 'would you rather drive a Honda or a Fiat'

This is a tangent, yes.