As aikidoka, shouldn't we be ashamed to say, "unless you connect to me more fully, I can't do anything but strike?" Nage can take action before uke has done what he intends, so I think "simple" grabs (grabs that are not engaging nage's center) are perfectly valid attacks - nage just has to "come in" more to make up the difference. It's the same thing you've described but paused earlier.
Well, this brings us back to the statement that Aikido is 90% atemi... Then I remember Peter Goldsbury saying, wrong... it's 100% atemi. This was summed up up in Saotome's Sensei's statement that every throw you do in Aikido is a strike or strikes that you CHOOSE not to do.
So, no, I do not in any way feel ashamed to inform an uke that of he comes into my space and does nothing to commit himself to altering my own aligment or restricting my ability to move the technique will be an atemi rather than some more user friendly response.
I am sure that most of us have had the experience of trying hard to do what the teacher just demonstrated with a passive aggressive uke who either won't commit or who disconnects in order not to go off balance. Could I do henka waza and change up what I was doing and do something other than strike him? Sure, I could... but why would I? That would encourage the uke to think that I was "required" to do something that he or she would associate with an "Aikido technique". I have seen people keep trying to get some technique on a partner who simply keeps breaking the connection to counter the throw. But the fact is that the throw just isn't there any more, if it ever had been. What is there is a strike or strikes.
Saotome Sensei always said that if you knew
the other guy would not, or could not strike you, ALL techniques were stoppable. This is what it means when someone says that Aikido is 90% atemi. Atemi is implicit in every movement we do. It is uke's job as part of his training not to put nage in the position of having to make the atemi explicit.
Besides, an attacker who grabs may not be trying to throw - he may be "indexing" for a strike, or simply preventing nage from blocking a strike that is on the way. So, grabs that don't seek to strongly disrupt balance are worthwhile attacks too, yes?
Ok, now we cross into non-standard attacks. I am not saying that an attacker "has to" to anything in particular in a real martial encounter. Many systems teach you to only commit to the attack for an instant at the very last possible instant. This makes moving them very difficult. Then when you introduce the idea of internal power training in to the mix, you start talking about folks whose ability to balance the forces of their bodies gives them tremendous power while at the same time making them virtually unthrowable. I know some of these folks. I do not think anyone I know could throw them without first striking them (not an easy thing to do).
When I trained many years ago with Ellis Amdur Sensei he once pointed out that most martial arts are filled with basic techniques which, you don't study because you think that you will someday be using them in combat aginst a skilled attacker. You study them so that no one can do them on you.
Aikido is full of techniques that, as your training progresses, are no longer going to work on you. There is a point at which there really isn't anything left but striking. Perhaps after applying atemi, you will have "cut the ki" of the opponent sufficiently to then get kuzushi and apply a throw. But it would take the strike to do it.
So, I do not see any reason to lead a partner to think that, as an Aikido practitioner, there is some rule that says I need to respond to his essential opening in some other way than any other martial art would, namely a strike. If the attacker is connecting as I have descriibed, his grab will help protect him from the strike. If it doesn't do so, then he will be struck. If it does do so, I can give direction to the energy of that connection and turn it into a throw, which is what we were practicing in Aikido. It is very much my partner's choice about how the interaction proceeds.
At the higher levels of practice there's nothing wrong with working with different paradigms. Then you can find out for yourself if what you thought was really true. But also, when you cross in to that territory, you start to leave the land of "safe" practice behind. Things start to lose the "kata" or form and start to get really formless. That's when you can start getting folks injured. Many people simply don't wish to cross that line.That's one of the things I appreciate about the "form: of Aikido. If we stay within the form, even though it might get very spontaneous and highly energetic, even impactive, it can still be done safely with everyone walking away healthy. So, I teach an ukeimi that is both martially effective, but is also still within the Aikido form and will allow outcomes that fit the form as well.
Anyway, that's my take on it.