1) D&D as was, was a game based on fantasy tropes, drawing from the rich veins of mythology, legend and fantasy fiction inspired by these tropes. The audience understood this. Gods in the game were real, they had a presence and impact. Races (used in the original sense of the word as a synonym for species) created by the gods. Good, evil, law, chaos were objective, tangible meta physical aspects that affected the world.
Creatures could be born into evil, designed as such by the gods.
Informed by Judeo-Christian influences on understandings of good and evil, they are evil. Born into this sin, manifestations of the chaos wilder lands and borderlands against “civilised” society.
Some of the most enduring myths (informed by the different cultures’ religions and understanding of what was good and evil) and modern fantasy are good and evil. Lord of the rings for example.
Metaphysical alignment is useful for particular kinds of world building and story telling, namely this kind of Christian-ish LOTR heroic fantasy. And, if alignment is built in to the structure and implied setting of the game, it is conducive to producing these kinds of worlds and stories and not others.
First of all, this is incredibly condescending. Perhaps you have the opinion that there are transcendent monomyths to all human cultures. But if you have the view that there are not are also knowledgable of and interested in the incredible diversity in "mythology, literature, and cultural history," that produces different kinds of tropes, stories, and worlds. That latter group might also be sensitive to the "cultural history" and context of fantasy writers and creators in the 19th and 20 centuries and how that might have affected their understanding of Civilization/Savageness, and the Borderlands.Those that have called for their removal recently, using either points 1 or 2 have shown a startling lack of respect to the game, their fellow players and ignorance of the wider mythology, literature and cultural history that has informed this game.
The irony is that the mechanics of 5e are actually good for heroic fantasy given the power level, whereas early dnd and osr games are more suited to ditching the good vs evil stuff and making the game about getting rich or die trying. As far as "lack of respect," for me the most central ethos of dnd is to have a lack of respect of the game, inclusive of both rules and lore. Make it your own!
Conversely, why can't alignment be an optional rule in the dmg? Why can't the game shift from alignment to some other way of describing motivation (bonds, flaws, etc) that might include notions of evil and good but in a slightly more expanded and nuanced way?If you don’t like something, don’t demand it’s removal from the book because it doesn’t fit your viewpoint (something which breaks the live and let live approach as it dictates what is acceptable or not to the wider community and stifles creativity). That’s not cool.
Personally, I'm in favor of keeping alignment around in some form, just because I like the memes.