the idea is good, but really hard to implement.
In older RPGs, you have to have enough charm to get extra dialog options, same can be implemented with D:OS. But to hide those extra choices, it could quickly become annoying like in traditional point-and-click adventure games where you must use keyword to use/combine objects(where you know what to do but have to try all the combinations of keywords).
Imagine a situation like this, is D:OS, there is a dialog sequence, where you ended up have this following typical situation.
"Did you slay the monster and avenge my son's death?"
Normally, a modern RPG won't ask you this, it's on a check list, automatically checked off and gives you exps. But say in D:OS you might be able to do the following:
1. lie about it( roll check against charm, bear the consequence if you don't actually kill the monster.)
2. tell the truth and give up evidence( like a +10 stat monster eyeball. )
3. demand more reward
4. kill the client( assuming that the monster is cursed by the client and ask you to help instead.)
So without reveal these choices upon dialog( ie. 4 might be hidden if you don't understand monster language or didn't do enough dialog with related NPC.) It would require a machine like IBM's Watson to understand nature language( remember we have several language ports), and related story info to determine the context you just input. In example 1/2, how are you intended to implement this?
player might type:
"I killed it, now give me my money!"
"Done!"
"It was a easy task."
In above 3 situations, game won't be able to tell if you mean 1 or 2. but can easily done, if you have high enough charm to show first choice.
I'd like to hear if you have better approach to this problem.