Always a quality contribution...
The pitching machine, while predictable, still throws you the pitch you are going to hit. If you are expecting to "hit" a right cross or a double leg, why is the pitching machine throwing yokomen uchi and katate dori?
You used a great analogy, but I still feel like we haven't gone to an adequate depth in this thread.
Depends what you mean by depth.
Effective striking in Aikido is also down to movement. Aikido is fundamentally an art of harmonious motion so even technically following that you should be through movement in a position to make the perfect strike. So that's factor number one.
I don't know how many train or are taught how I was but our teacher used to show us and emphasize perfect harmonious movement but at the same time, usually using us painfully, show us why imperfection leads to getting hit.
Then there is the point of effectiveness of strike on it's own. Well if you listen to any really good Master of his art you will learn something about this. I think it was Suzuki, the Karate man who said that even if his martial art was practicing one punch then it would as a martial art still take a lifetime to perfect.
Now also any 'deluded' notions on effectiveness can easily be corrected in my experience and more than that can be done in slow motion at which point the person has all doubt removed.
Another thing we do and did was practice of strikes alone, drills. Have you ever done them? You practice until the strike is unstoppable.