While in theory I don't disagree this is possible, I first want to point out that you are again insisting on a) the primacy of the truth that no one judges oneself better than oneself ("It's not important or necessary for the GM to impose restrictions based on their understanding when it might be in conflict with my own...the player who better understands the morality of the character himself") and b) the primacy of getting what you want and think you deserve ("resolving them based on how I feel the story should progress when handling them"). I'm not going to quibble over the truth of those statements, we can for these purposes except them as valid, but I do want to highlight again the primacy you are putting on your volition and judgment and note that this is again at right angles to how the majority of people who live lives of service, duty, and devotion to a code see the world.
And secondly, while I agree that there are people who can turn the mirror on themselves quite well, I find in practice this is a pretty rare skill. Seeing truth clearly is hard. Self-evaluation is really hard, and I'm not sure that 'this is my character' is sufficient distance from 'this is me' that for most people it's easy. As I said earlier in the thread, I find that 90% of people can only role play themselves. Maybe you are really good it. And maybe you are just an incredibly good role-player. Maybe you have the same stance toward your PC's that good DMs manage toward NPCs. But, regardless, I find it strange to think that you expect to simulate duty by a system that means you are never subject to any constraint but the ones you place on yourself. That's a really low standard of obligation.
I guess the problem seems to be that I'm not judging myself in any way. I'm judging a fictional character as part of a story. I am not my character. There is no "mirror." There is no "self-evaluation."
Any constraints should be built into the rules of the game and not DM fiat. I suggested several ways up thread on how to handle that. Neither of which is in conflict with the way I prefer things to be handled in a RPG. If "duty" is a game rule than to resolve that rule there needs to be mechanics for arbitration (such as a religion check to determine if the action caused a lapse of duty). If it is purely narrative in function than there needs to be ownership of the narrative (which for me is the player) and consequences (which for me is the DM), neither of which are mechanic in nature (the character don't lose character abilities).