I have a hypothesis and I want to ask your opinions of it. (I'm going to do some vast generalizations here based on my own experience. When I say "We" I'm speaking from my own experience)
We aren't emotionless, we just lack affection. We don't form bonds with things, we don't care about things, which is why we don't have anything to feel emotions over. It's not that we can't feel, it's that we have nothing to feel for.
Love is affection for another being. We don't feel affection, so we don't feel love. When someone dies or goes away, we don't feel sad, because we don't have a bond with them. We don't feel hatred when our family is hurt by others, because we don't share their pain. We often don't even fear death, because we don't feel affection towards our lives either.
However, we do feel frustrated with things. We feel frustration, because it's origin isn't in bonding. It's about things not working as they should, and it's annoying, and because it not about bonding, we can feel it. We may also feel hatred, if we are physically attacked in an unreasonable manner. Someone is a dick and making us uncomfortable with his dickness, and it angers us, because it's not about bond, it sources from frustration.
I can even feel sadness in a certain situation (for background, I became schizoid because of environment). My another hypothesis is that people can only understand feelings they have felt before or if they can imagine the situation. Meaning, you can understand what losing a loved one feels like if you have felt it before, or by imagining what it would be like if someone close to you would die. Because no one died when I still felt love, I can't understand the feeling today, because I don't have a loved one now. However, when by some impetus (music or certain phrases) I go back to the days when I felt all alone as a kid, I become so sad I feel sick.
If I didn't have emotions, I shouldn't be able to feel that sadness, right?
So, what do you think? If you disagree strongly, perhaps I'm not schizoid after all, but I've developed some form of autism or something instead.