I think the intent behind the photography counts for a lot in whether it should be allowed or not. Some people are definitely camera happy, and any pictures of artwork might just be "Some art I saw at the museum" to them. Or someone could use a camera very little and still have little attachment to the artwork. If taking a picture is taking away from the original, how can we possibly justify holding onto memories, which, for some people, are even more true to the spirit of the artwork?