It would take an entire Ph.D. thesis to elucidate Tolkien's motivation for Gollum, but you're right - it's off-topic. This is a touchy issue for Tolkien fans, who view themselves as tolerant and open-minded. It's an even more sensitive issue for British Tolkien fans, because all they have to do is look at their various newspapers and magazines to see that the same anti-semitism prevalent in Tolkien's time is still there today.