Re: Beginners should not be allowed to act as uke.
I agree that you should try not to have newer/novice students working with other newer/novice students. That's why I try real hard to never allow pairings like that if they can be avoided in my dojo. However, there is much (as you allude to) that can be learned on the part of uke and nage (tori). Uke learns quickly that proper ukemi is important and exactly WHY it is important. The other lesson is for nage to learn they have to take care of uke and adjust the intensity of their throw according to uke's ability to take ukemi. That is where Jigaro Kano's lesson of Mutual Welfare and
Benefit (Jita Kyoei) comes into play.