I was under the impression that there is a practical requirement for the run and break in some aircraft. A hunter or L29 for example? Both of these kinds of aircraft fly from airfields without full ATC, so it is important to expect an R & B. Following on from this it is a good idea to understand the R & B and be prepared for it.
I personally have been in the circuit when a Yak did a R & B and it did not cause me any problems. I think on a day with good vis and not much traffic it can be done safely, and I imagine it is good fun to fly.