My particular take is to teach a counter, usually by demonstrating it for stiff, or overfocused attacks. For Ikkyo I find a common mis-resistance to be to stiffen up the shoulder and upper body. I usually talk about their being options, and snap a kick into the groin area.
This is of course all flash and no bang, but I do it with the intent to contact strong enough that it usually takes uke out of "be stiff, or don't be ikkyoed" long enough that the ikkyo then drops them like a stone.
My other option, for a more Aiki-ish alternative, is to slide the front foot as far as the uke's lead foot, and hook the heal with the arch of my foot. I slide my lead hand from the upper arm, or wherever, to the other side of the neck and weight underside/pull from the base of the neck, around and down, like peeling an orange. At the same time I pivot on the lead food and bring the person down. This also has the benefit of dropping the uke right in front of you for potential control techniques, and protecting the head in the fall for situations when you have parameters for use of force.
Instead of telling the uke they are being a bad uke, which only feeds the skeptic inside, I have the nage practice this alternative, and that switch back and forth. The uke is to occasionally choose to lock up the shoulder, and typically to stay relaxed enough not to open themselves up to easy strikes or the counter throw. "kokyunage from blocked ikkyo?"
This way by playing in the paradigm, you can encourage the students to see the learning process and learn to make the correct decision when someone who should be
purposefully tries to be
For ikkyo ura I use an armbar alternative, or nikkyo. etc. etc. I think the pedagogical key is that you provide a clearly defined paradigm for alternative A and B, and discourage the immediate overwhelming data to sift through in an anything goes scenario...