Re: Why these techniques?
First off, let me just say thank you "ward ward"; back on track!
While I agree, with what I believe you are saying, that these are the techniques we use to explore Aikido, because learning Aiki is the true nature of Aikido. I think what Michael is asking is why did O-sensei choose these techniques (Ikkyo, nikyo sankyo etc.) to explore Aikido, and further what relevance do these techniques hold.
I am of the opinion that O-sensei chose these techniques because they are what he and his students knew when he started his huge and final exploration into Aiki (these techniques being a common ground to use for exploration, and something that he knew well), and these techniques are directly from and not developed beyond a weapons system.
Now as to your analogy of people being weapons, I would also agree, I would call a navy seal a weapon, I would call an special forces agent a weapon, but in the context of this conversation, I am talking about a weapon specifically carried in the hand, a weapon that gives a distinct mechanical advantage that an empty hand alone does not have.
I think hearing from other people who are reading this is nice, the conversation is getting a little stale.