Why is it that questions of a controversial nature usually get more replies than questions that aren't controversial?

I've noticed this on other sites as well as this one. Questions like "What is your favourite TV comedy?" or "Do you think Pink Floyd were better with Syd Barrett or after he left?" are bound to attract different answers yet questions like that are lucky if they get 20 replies, while questions about politics or religion usually get 100 replies or more. Why do you think that is? Who even wants to discuss politics or religion anyway, when they can discuss entertainment instead?