But one of the things you learn by doing that is that strength and (physical) power don't help much if the other person has more of them, and therefore relying on them in a self defense situation is extremely unwise.
The point that I would like to make is that whilst it's fair to say that atemi striking is effective with strong physical power, that is not true in all cases. Atemi points are the weakest points in the body and injuring them does not in all cases need a great deal of force. In Atemi Jujitsu we are trained to strike at the side of the kneecap with a Muay Thai styled kick which needs very little force to take someone's kneecap off. Ribs are often easily broken with the correct style of punch where the knuckles pass between the ribs and enter the rib cage. Throat striking is another effective use of Atemi.
Whilst it's not Aikido I am aware of a young female who used her Hapkido training (Hapkido like Aikido being from the family tree of Daito Ryu Jujitsu) to defend herself against a rape situation in a local park. She with not a great deal of strength applied a finger lock that broke the assailants fingers, hand, wrist and dislocated the shoulder. She was in tears afterwards, not because someone had tried to assault her, but because of the physical damage that she had done to this person. Granted fingerlocks are not strikes, but they are a good example of atemi used in the correct way for self defence purposes.