Hmm...I thought atemi was just something to distract your attacker so that one could gain a split second of time to put them in a nikyo or a similar hold. Not something meant to really cause some damage.
Think about it though. "Hmmn, I think I'll hit the sorest nerve point I can reach with a single knuckle, letting my whole weight go into the strike."
Distracting is where you try and get them to charge at a towel you're waving, and even then sometimes you have to jump over the protective barriers surrounding the tatami. Or something.