I'll tell you why... Ghost Hunters on SciFi Channel and Paranormal State on A&E scare the CRAP outta me!!! LOL!! I'm not lying... I love those shows!!
But for real... the existence of ghosts/spirits/residual 'energies' after you die defy my perception of the human existence. I think most Atheists agree that we are nothing but a small step up from chimps and the fact that we cry when someone else cries does not make us leaders of the Universe! Just because you perceive your emotions a profround and earth moving, at times, does not mean that your existence permeates space and time. It's just neurotranmitters and synapses... nothing more. The same thing can be found in your pet dog's gray matter (I heard about a study on Calling All Pets on NPR that dogs have similar neurotransmitters and receptors in their brains as us). Just because we have cognition doesn't make us special enough to float around after we're dead and rotted and interact with our loved ones (who will also be dead one day).
The next time you pass by the dead squirell at the end of your street that has been there for a few days, realize that WILL be you and it WILL be too soon whether it's tomorrow or 80 years from now. All of a sudden that TV show you're watching doesn't seem that interesting, and that 99 cent hamburger seems like a complete waste of your precious time to choke down. I'd get a steak instead, and enjoy it while I can.