So my take on this is that the standard alignment system should probably be universally upgraded at this point by the simple fact that since that system has been initially invented, games have been getting more and more realistic. By that I mean the expectations we consumers and gamers have toward our games has risen. Due to this we have to ask ourselves when we talk about this alignment system from Dungeons & Dragons how could we modify it to fit real humans?
Well, first of all real humans actually change. We are volatile creatures and through wisdom we can change our habits, our expectations, and especially and most relevant, our ideals. If it's true that our very ideals about life change throughout our lives, then we can deduce that any alignment system would need to also be able to change with the person.
In other words, if I'm a 19 year old and I consider myself Neutral Good, this might only be due to the fact that all I've experienced thus far in my life are things and challenges that I've been able to overcome no matter how difficult they were, you overcame everything so from your perspective, with effort anything can be accomplished. Such people will typically be pretty good people. However that same 19 year old might go out into the adult world and just get taken advantage of by all sorts of people, they might exploit him for money, or anything. Perhaps he will witness people he felt were his best friends in life betray him, or a woman cheat on him etc.. Etc.. The point is, by 30 perhaps that same neutral good kid has now become a chaotic neutral person. Does this mean that his current personality betrays the alignment that he used to be? I think it just means he grew up. That is why I say ultimately alignment cannot be static. Ideally it will change as a person changes.