It can be an exciting challenge, that's for sure. I love doing all the research, gives me an excuse to read text books for fun. Haha. I admit when we play D&D we tend to leave dragons as a whole pretty much alone, which might be in part due to what you mention. We like to bring in a lot more Tolkien into our games, though, and my dad, our GM, rewrote a couple of the elven races into straight-from-the-Silmarillion elves. I guess that's D&D's saving grace, you can redo as needed.