Drows being evil by nature is not a third edition thing. You can trace it back to Advanced DnD, from their very inception. If you look at old art from that period depicting the Drows, you can see that they manifest a lot of the anxieties of the 70-80ies (POC, violent matriarchal society, etc).
That's the kind of oversimplification that's liable to get the thread locked :s
