Well.. hypothetically speaking, suppose I was a room temperature IQ subhuman near-neanderthal, who unwittingly trespassed into someone's home, and then because they were confused and angry at my presence, I got scared and instead of leaving I just couldn't help but escalate the situation and kill them.
Now we all "know" that harming others and killing is wrong, but isn't self defense okay? And if an innocent guy ends up dying because I felt a little stressed and scared, but like, I -really- didn't mean it, that's still understandable?
You see.. if the person in this hypothetical situation was sincere and genuine about all this, sure it's easy to empathize with that and throw all rationality out the window. But the problem is we as a society do have laws to sort out these situations, and to figure out who's really in the right and wrong.