I think the romans just did what most slave-owning cultures did: they removed the source for trouble in their slaves. They knew very well that the only way to effeciently run slave business was to emasculate the male servants. After all, you geld stallions and bulls too, don´t you. Sometimes it was ...

I think that was a smart thing to do by the Romans. Every slave-owning culture knew very well that they had to remove the balls of their captives to turn them into subservient slaves. That was standard in most ancient cultures, especially in Rome. After all, you do not let bulls run around ...