It does ... but I'm just not sure it should give the same kind of advantage that the other situations give. For example, a Rogue Sneak Attacking his foe, just because his foe is prone, just doesn't run cinematically in my head.
I'd love to know if I'm wrong, though, and if Sneak Attacking a prone character makes perfect sense. Because I can't actually pin down a reason why it doesn't "look right" to me.
Why doesn't it "look right" to you?
You're lying on the ground, instead of on your feet, ready to fight. It's a terrible position to be in during a fight.
You have your way. I have my way. As for the right way, the correct way, and the only way, it does not exist. - Friedrich Nietzsche