>Let me guess, it's an optional rule for player characters too now?
Do you have mild dyslexia? I'm honestly asking, because I explained in the very post you quoted how Unaligned worked, and the context makes it perfectly clear as to what it means. So I'm genuinely curious if you have some form of dyslexia.
I mean, either that or you're just not reading before responding.
Also, what do you mean by "they actually invented unaligned"? Unaligned was introduced in the 4E PHB, back in 2007. That makes it ten years old at this point. It's been around for about a quarter of D&D's total existence (presuming we use 1975 as the first publication of D&D). Arguably the concept goes back even further, with the "Allegiances" of d20 Modern and the fact that your character could be literally unaligned, i.e., not have an Allegiance (and monsters in d20 Modern, including animals, rarely had Allegiances, either). That would make it date back to 2002, meaning the concept has, in the context of d20-based games, been around for a third of D&D's total lifespan.
In my games, humanity taken as a whole doesn't tend towards any alignment. However, the vast majority of people have a practical limit on how far they're willing to go.
A Good person isn't expected to abandon his family and travel to Uganda to help fight AIDS, for example. He has personal responsibilities at home, and probably doesn't have the skill set or natural ability required to help out much anyway. A Good person is, however, expected to do what he can to the limits of his ability to achieve Good, such as donating to charity or working to increase awareness of the AIDS epidemic.
Likewise, Evil doesn't necessarily mean hand-chafing villainy as you contemplate taking over the world, nor does it even mean killing people. Evil is usually as simple as just not caring about other people and only looking out for yourself and your own advancement. Ebenezer Scrooge is a perfect example of "mundane" Evil.