Never happened to me, either. But I don't think creators (or anyone) not responding to my mail is rude. Everyone has time restraints, and these guys aren't getting paid on the clock. They get paid by the page. Taking time to answer all the fans is taking time from increasing their page count.
Also, I sometimes feel that the social media of certain creators, especially twitter, is more like a conversation between friends. Me interjecting myself in there sometimes makes me feel ... uncomfortable and pushy. But tumblr or formspring, where the creators have an 'ask' button, I don't hesitate to ask, but POLITELY.