(first part of the post directed towards Ian's comment)
Please refer to the later bit of my post where I talk about the possibility of the word "atemi" meaning different things to different people.
If there are videos of O Sensei punching and kicking people in later life, this is not neccessarily an indication that he was still practicing "atemi" when you define that word to be the striking of pressure points. It is one thing to hit someone, and quite another to hit someone in such a way as to activate pressure points.
Usually, pressure points require a very specific direction of application, and to achieve any of the really impressive results (knockouts, etc), the strike must generally activate three or more points either at the same time or in rapid succession.
Perhaps we also need to draw a distinction between atemi (defined as pressure point striking), and use of pressure points to augment technique (which I have heard referred to as tuite, but that word might have other meanings, so let's keep our discussion in english).
I have heard that the former can result in training fatalities if someone hits too many points at once, or if someone knocked unconcious does not recieve immediate attention, or if they are practiced too much. This seems like ample reason for O Sensei to want to ban their practice both on practical and philosophical grounds.
However, the second kind can be really quite neat to learn, and very helpful in augmenting technique. In fact, the way that many people do yonkyo is such an application.
I'm not sure I entirely agree with saying that these are a "good way to bridge" between practice of a martial ART and a self defense, but that is simply because not all people have all the same pressure points, and they are never in exactly the same place. I for one would never want to rest my personal safety on being able to accurately locate multiple nickel-sized points on my attacker's body with any kind of speed. But if you train to have these points as an added "bonus" to any technique you do, that's just gravy.