Why is singing haram?

I know that according to most sources, singing is haram. Yet, I cannot see **why** it is so. It is claimed in several sources that singing is "idle talk", that it can "mislead you from the path of Allah", that it adds "hypocrisy to the heart" .... yet, all of these arguments are not arguments, they are baseless claims and accusations. *How* exactly is it "idle talk"? Surely there can be a lot of purpose behind ones singing. *How* exactly does it mislead you from the path of Allah? Surely one could be singing about good things that are in accordance with the preachings of Allah and Muhammed? *How* exactly does it add hypocrisy to the heart? This last one especially makes no sense to me. There are many things forbidden in Islam and many of them are based on strong arguments - yet this one about singing? I don't see why it is forbidden, and, honestly, I don't think it **is** forbidden, I think this is an example of fundamentalism gone wrong.