Shouldn't there be pushing and pulling, but not overt pushing and pulling with the arms?. More along the lines of pushing and pulling with the lower body on contact.
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.