The strange thing about D&D is that the rules are pretty bad, but the game is good. Why? The designers simply put so much detail into the universe that a Dungeon Master doesn't need to wing it, while simultaneously leaving the DM a great deal of freedom. Other systems which have had comparable levels of detail (Rifts, for example) are so much more complicated in their detail since the worlds are enumerated: there is only one Mexico overridden with Vampires. In D&D, the DM has the freedom to make the kobold wizards powerful even though kobolds 'should' hardly ever be able to cast magic at all, and never well; the DM can ally the Drow with the Gryphons. In Rifts, a knowledgeable player could simply say, "No, they aren't". In D&D, you can say, "They are, here!" while still having a great depth of material to draw upon.