Any argument from particulars of fiction, that AD&D ought therefore to be thus and so, is to miss the goal of design and contradict the designer's own statements. The game was most definitely not intended as a "Tolkien simulation" or "Moorcock model". What Arneson and Gygax borrowed from those sources were ingredients to add to a stew, the flavor of which was distinctively its own but that pretty clearly emphasized players taking the initiative and pursuing ambitions.
Per Gygax, "the most immediate influences upon AD&D were probably de Camp & Pratt, REH, Fritz Leiber, Jack Vance, HPL and A. Merritt." It is in the areas of overlap among those, I think, that one might most fruitfully expect to find themes given prominent expression.
On the other hand, although AD&D was very clearly Gygaxian it was not solely that. Much by other hands had been woven into the fabric of D&D, and the Advanced books included some things more on the merits that others saw in them. The basic structure was still the same modular one, more a trimming of what had "organically grown" than a truly systematic "design" (along the lines of Hussar's observation). The influence of Tolkien and Moorcock on the market for the game was due a tip of the hat, as were the interests of other parties (such as those enjoying the various weapon factors, or psionics). It was easy enough to dispense with whatever one happened not to find indispensable!