I'm personally not a big fan of random selection of punishments. I think punishment should come directly from the decision of the dominant: "You did that, therefore this will happen." The danger with random selection is that it may result in a severe punishment for a relatively minor transgression; or vice-versa allowing the submissive to "get away" with something big while receiving a light consequence.

In my opinion, there should be a distinct line between punishment and play, even if there are overlaps in the instruments/activities. Punishment is intended to ultimately correct an undesirable behavior, so it should be more logical.

Now the random idea works well for me as a play tool. "Let's roll the dice and see how lucky you are ... oh, you poor dear."