I don't think you "should" feel anything than what you naturally do feel. Death is often about mourning their life WITH you. In a way, we cry because we are selfish and we want our loved ones still here with us. Therefore, it makes sense that you wouldn't really feel "anything" for the death of a person who didn't impact you in your life positively.. and I think that's okay. It doesn't mean they were a "worthless" person, or any sort of bad person because I am sure there are others that would be more impacted by the loss, but I don't think it's natural to try and force sadness or anything. If you have to force it, it's just a mask anyways, so.. just feel how you feel and let it be. I think anyone would probably want to offer their condolences to those who are hurt by the passing, and hopefully whoever it was that died is at least resting in peace, but if you feel nothing, you can't help those feelings. It's why they couple "love and loss" together.