In my opinion, this is how "aiki" is meant to work. It's how I teach it. The way you describe it, there's an almost simultaneous movement. That's unlikely to happen. So, how do we explain teaching that? Well, if you're actually moving, responding to the opponent, and striking, then you will sometimes find yourself properly in motion at the right moment. I see this happen from time to time in boxing: one guy throws a good punch just as the other guy decides to slip to the outside. That's a perfect set-up for aiki-style techniques, and it's not about responding to a single, specific attack (as the classical training seems to suggest), but about working the situation with other tools until the right moment opens up, then taking advantage of it. So, we don't have to be preternaturally fast, have precognition to know what's coming, or any of that. We just have to be able to hold our own and recognize the openings. I don't think a pure-aiki approach can provide that.