A couple of comments:
The "scientific report" that is cited here in a couple of places doesn't say that the light from flashes won't hurt paintings. It says the light from flashes under the conditions examined in the report won't hurt paintings significantly compared to ambient light. It did not examine all conditions, nor did it examine all paintings. I doubt that light from flashes will hurt the paintings, but I'm still not sure. Until recently, a large number of scientists thought that global warming was a myth. As it turns out, it probably isn't. If you go back through the history of reports like this, on a wide variety of issues, you often find out that things that were reported unharmful (cigarettes, DDT) were, oops, harmful, and even deadly; and some that were supposedly harmful, were, oops, not, except for the people who got trashed by the report (agar.) I don't know where this report came from, or if it was published in a refereed journal, but it has many of the characteristics of a "some guy" report.
But, as I said, I suspect that flash doesn't do much damage. The real damage is that it makes certain pictures in certain museums unviewable, and that it helps create a funhouse atmosphere in art museums. I've been very discouraged by the reactions of many people on this forum, which, after all, is concerned with the making of visual art. They seem to feel that Disney World conditions in art museums are just fine and democratic and all the other bullshit trotted out as excuses for people to shout down the thinking process. I've gone to NY annually for a very long time for the specific purpose of looking at art. I did not go to MOMA the last time I was there (in July) because of the conditions in the place, which have become nearly intolerable. That's the first time I've not gone to MOMA since sometime in the eighties.
But here's a question for the people in Chicago: why is the Art Institute so much better in terms of viewing conditions than the big New York museums. Is it because the Institute is physically harder to get to than the NY museums? Or maybe Chicago just doesn't attract the huge crowds of tourists?