What you say is true: The D&D Rules have always been limited. If you play the game by only the rules, that is a hexcrawl "wargame", as that is all the rules cover.Don't really agree with this bit. D&D is a quite limited game! Later editions have branched out SOME, but it's fundamental paradigm is designed to motivate a specific sort of setup where GMs provide specific pregenerated challenges and the PCs navigate them specifically to achieve a certain type of win conditions. It really has almost zero support for anything else, even in it's most modern form!
But see.....that is not what happened. People took D&D and made it more: more then the sum of it's rules. People started to act out the game, and play roles. People role played. Beyond the rules.