Yes, a reasonable juror would ask the question, "Why wouldn't you ask, 'Who is it and why are you knocking on my door?' before even opening the door late at night?"
The standard in most cases like this is "What would a reasonable person do in this situation?" A person fearful enough of a threat to carry his firearm to the door might reasonably be expected to ask (through the door) who the hell is knocking before opening the door and firing without conversation.
When you walk to the door with a loaded firearm, you are proving you expect trouble. When you take no reasonable steps to rule out a harmless visitor, you have acted like someone who WANTS to shoot first and ask questions later.
That is a flawed premise. I might say that answering your door at 12:30am without a gun is asking for trouble.