Actually, I prefer trying to avoid also moderate pushing and pulling, whether it's from the center or not. I don't know if it's possible, but it's definitely worth striving for.
When tori is really accepting the attacking force and direction, the techniques can be done with almost no pulling or pushing.
The pushing and pulling that I object to the most is the one happening at the moment when uke's balance is already gone. Excessive force at that moment is "overkill", really turning the defense into an attack.
There's two things going on in what you are saying Stefan... At least that's how I am seeing it.
First, strictly from the technical standpoint, I think this issue is often one of terminology. Some folks use "push" any time they are talking about energy going out to the partner and "pull" any time they are referring to bringing the partner to them. Personally, I don't use those terms with my students because they have an existing association with what those terms mean in their bodies that isn't correct. When you tell the average person to "push" he will fire all the extensors in his arms, and if he is trying for more power will "thrust" with the legs. If you tell them to "pull", they will fire all the contractors in their arms. In decent Aikido, neither of these things ever happens. So, I tell my students that there is no pulling or pushing in Aikido. Then I teach them the proper way to put energy out or take it in.
But the second issue, which is getting mixed in here, is more of a value judgment concerning what one is trying to express in ones technique from a spiritual / philosophical standpoint. You equate what is being called "pushing" with an attack at the partner. I see it simply as a value neutral expression of energy / movement. If done correctly, certainly without the intentional components of an attack, it is merely allowing the technique to express itself via, a perhaps "explosive" yang energy.
If it involved "pushing" as I described it, as a muscling, fire of the extensors, thrusting with the legs, etc I would say it's bad, not because of the "attack" but because doing so doesn't actually work and puts one off balance and open for counter.
But if this can be accomplished by staying relaxed, centered, and doesn't have the emotional content and tension of aggression, then I have no problem at all with it. Certainly much of what the internal power guys are referring to is massively and explosively yang and will blow you across the room with seemingly no effort from the nage.
Also, from the larger martial standpoint, this so-called pushing, when it is being done properly is basically providing the same platform as you would use in atemi. It just depends on when you accelerate the energy. If you accelerate the force before you make physical contact with the partner it's a strike. If you accelerate the force after you make contact, it will move the partner without having the "impact" component. As far as I can see, one needs to understand and be able to do both depending on the circumstance.
Of course, I was trained by a teacher who believes that steeping in and cutting the partner down is a perfectly legitimate expression of "aiki". He would look at this an attack on the partner but rather it would be taking the space away from the attacker that he needs occupy in order to complete his attack.
To sum up, when you see Yasuno or Endo, or old films of Yamaguchi seemingly "pushing" their partners away as the throw, I believe you are seeing striking that they are being kind enough not to do. In the martial context, you would not typically throw an attacker away from you. You drop him straight down where you can deliver the finishing impact or breaking technique, or perhaps apply a lock or pin for control. So when you see Aikido folks doing these throws in which it appears they are pushing the partner outwards into his roll, I look at this as practicing all the components of striking without actually manifesting the energy as a strike. Much more fun for the partner...
Anyway, that's my take on it. I definitely see it as value neutral. Just another way the energy can be run.