I agree that it's a very good example that following Social Proof can be misleading, but I still think it makes sense as a strategy to minimalize the risk of making a very bad decision. I realize that it's preety vague ant thus not exceptionally interesting point though :).

Actually, you can even point out that a decision made by the majority can't be the worst one in a social sense and I don't think it's completely stupid - after all, if you're in a social group and don't know what to do, it's always good to make sure that you won't end up worse that the majority since it happens quite seldom that the majority ends up very bad.