As for striking being "unnecessary", that's kind of an odd way to put it. Necessary for what? Unless you qualify that, ultimately nothing is "necessary", not even oxygen -- it's just that without it, there are certain consequences. The same is true of striking skills. I have no doubt that many aikidoka view striking as unnecessary, and also no doubt that for at least some of them, it's true -- their aikido is good enough to be the only tool they need if they are attacked. For the rest of us, I think it's wise to consider how to do effective atemi. That does not have to mean learning how to administer a knockout punch, but it does mean going beyond vague and ineffective hand-waving.
Absolutely agree. I think my point is that you don't get to a place where striking is unnecessary by focusing on how to break boards (or jaws). What role does atemi play in successful technique? If teacher X takes out (overt) atemi and his technique still works, what's going on?