As for atemi to facilitate technique, I never hit anyone with any force of contact, but with a lot of force of intent. Having a long karate history, I can stop with that hair's breadth of contact, but it's enough to make uke move.
I agree with a well executed atemi it is enough to move uke's mind, the body will inevitably react, therefore allowing progress towards the desired conclusion. Which in the case of aikido is to throw or immobilise.
This whole question of what is 'good' or 'bad' ukemi in regards to resistance, seems like a discussion that will engage aikidoka for a long time to come.
Good aikido surely looks for the path of least resistance, so if resistance is present, nage does not go against the resistance but with it. This it seems is not the easiest of skills to develop, as naturally people want to fight fire with fire rather than water.
I know that in this modern age, it is very common to teach uke to throw himself off balance with his attack and never resist nage's technique. But if he CAN resist nage's technique, it's NAGE's mistake--not uke's. Rather than having an evil, punishing attitude toward uke, we need to look closely at ourselves.
I am unaware of this common trend that David speaks about. Although I train in a 'soft' co-operative environment, throwing oneself is positively frowned upon. The other day on the mat with my teacher he was watching some practice ( high grade ), he started looking around the dojo and asked the uke if he knew what he was looking for, the uke seemed confused, sensei said - "I am looking for the film crew, as you look like you are auditioning for a film"
I do agree that if uke follows nage's technique with non resistance, if the technique is 'wrong' uke's non resistant following will show up the point that it all 'locks up'. I will often use this as a basis of finding out when I can't obviously 'see' what is going wrong with a students practice.
There is no need for an evil punishing attitude towards uke or for that matter nage if something is not right. Both roles are a practice in the priciples of aikido. Both roles take time, practice, and focussed intent to improve. Having said that different teachers obviously have their own background and agendas to work from, and how they make ukemi themselves is their desired approach.
For me the 'art' of ukemi is an honest search for the truth in the technique, you can't find the truth with a closed mind, you have to be free and open to explore the extremities of what is and isn't in the movement.
I sometimes get my students to be fully resistant for demonstration purposes to show that it is possible ( and often even easier ) to overcome such resistance. It is also quite 'tricky' for the uke as their own relaxed co ordination is diminished when they create the tension of 'resistance', thereby making it harder for them to escape without 'pain'. Then we go back to non- resistant training
Just a few thoughts,