First, what's a controversial topic? Abortion? Definitely. One religion over another? Yes. But then there are topics which can have strongly opposing viewpoints but which, in my opinon, can be openly talked about/debated, e.g. casino gambling, a political contest. The goal there would be to have a balanced and rational discussion, ideally with all sides represented at the same meeting--but that's not practical given the limited amount of time we provide each week, so we perhaps have to settle for something like consecutive weeks. Those would be controlled by the Program Committee.
I think it's another matter for some member to stand up during Announcements and proclaim his/her views on some sensitive topic without having been asked to do so and without providing a balanced argument. (And anyway, Announcements should be limited to 30 seconds and should be limited to who, what, where and when. And the President should be encouraged to cut off an inappropriate speech or to comment at its end that it was inappropriate. It's OK to ruffle a few feathers.) ----Hub