[PvK]

Because (again, personally) it seems to me D&D is its own genre (and one that doesn't appeal much to my personal tastes), with a rich history originating in often rather ahistorical and nonsensical goofball inventions from the clueless gallery, even if they have improved greatly since the early days. If one wants to be a part of the genre of D&D and games that have borrowed from D&D, fine. (Nethack is a good example of a game that I really like that does borrow from D&D, but I'd probably like it better if it didn't.) But if one wants to do something unique and/or historical, using D&D as source material would, I expect, tend to import bits that originate from D&D rather than history.

PvK