Different games exist because different brains exist
Just as person X chooses Merp in order to play a Tolkienian rpg, while person Y chooses the recent "The One Ring", (and finally person Z goes towards Decipher Lotr rpg),so is with the multitude of fantasy rpg's published in history. There will always be those who don't choose D&D to get their fantasy experience.
But, among these guys: X who plays Merp, Y who plays TOR, and Z who plays Decipher Lotr, who is having the nearest possible Tolkienian experience (that is, the experience which resembles most- which is closest) to a Tolkienian flavor? Who made the "right" (or the wisest) choice? (i mean, apart from the efforts made by the players in creating a worthy game experience, solely taking into account the rule system adopted).
I think there is not an answer after all, and so is with fantasy rpg's.
But this at least proves that it is impossible to ascertain that they who choose AD&D made the "right" choice. Fantasy might lie somewhere else than in TSR's tomes.