The notion of alignment in RPG's and Fantasy fiction seems to refer back to the works of Michael Moorcock, particularly his Elric stories. The elric stories date back to the 70's, and were very well known at the time. The real evidence that they influenced Gygax comes from the fact that in the Elric stories the Lords of Chaos happened to be evil, although the good could serve them, such as Elric (The Man-of-Sorrows moral ambiguity of this character is for another node), or Rackhir the Red Archer. All the characters of any worth had explicit alignments, usually with an explanation for that alignment, usually to do with group affiliation of some sort.

Lest anyone think that Moorcock is entirely to blame for being a running-dog lackey of authoritarianism, note that he plays with the concepts of alignment throughout his huge body of work, so in his Blood trilogy, the Devil is the head of the Lords of Law.

This worked all very well in Elric, and in Moorcock's writing generally, as it served as a metaphor for extremism, and a backdrop for good, escapist dramatic conflict. Also, as characters had alignments for a reason, they didn't work as pure stereotypes: could be a source of angst and drama in characters' lives. In D&D, etc. it just seemed to me to suck. It didn't add anything. It just seemed to encourage gaming-by-numbers, as players could just do something "chaotic" or "anal""lawful" to give themselves a sense of roleplaying.

This is why new language features should not be included in production languages.