Please excuse me. I don't want to offend anyone. Really.
I think understanding (or in my eyes misinterpreting) pain as an element of aiki-technique is more something you do on a beginners level then on an advanced level.
You do not offend me (wouldn't know why? Opinions differ, but that's no reason for me to be insulted!)
Pain is an element of aikido. Aikido techniques can be incredibly destructive (ikkyo: breaks the arm, knee to the face; irimi nage: smash the skull on to the floor, elbow to the face; shiho nage: break someone's back etc etc). After all, these techniques used to be effective on a battle field.
I think it really depends on which style of aikido you train. Where I train, we don't go soft on eachother. If an execution of a technique doesn't feel right, we won't go down. Attacks are attacks, if they hit, it'll hurt. I've seen aikido video's on youtube where people seem to dance more than they are practicing a martial art. This can be very good if you want to do a harmonizing exercise, but the real-life applicability is zero.
I don't practice aikido to learn how to fight, mind you. I hate violence as much as the next guy. Still, I am studying a martial art, not fitness or yoga. Pain is a part of that, as is learning how to deal with it.
The reason I think like this about pain in aikido is probably due to the background of one of my teachers: one is a 7th dan in Jiu Jitsu (and 4th in aikido), and believe me, you do not want to try and resist his wrist locks.