They weren't impatient for the boys to turn into cartoons again. They awarded sympathy gave compassion. Because deep down they had found parts of themselves in the characters. You said it George.
I do think sometimes there's danger in guest appearance mania. I've seen too many examples that sound cool on paper like 'Oh get that guy to sing the hook on that guy's song ' and then that's all it is. It's a cool idea that sounds good on paper.