I like to work with beginners to a degree. Their reactions are refreshing.
But, I do not believe that beginners are the best uke to work with.
I want someone that's giving me a serious attack, that's working to out manuever me, to maintain their balance, to reverse me, to exploit any hole that I give. Also someone that has good enough ukemi that I have a greater set of options: to change technique as appropriate, to give different atemi, to counter-reverse.
Beginners, even with experience in other arts, just aren't up to that level of training.