They should be regulated at the very least, and a lot more restricted in the claims they're allowed to make. Lots of herbal supplements actually do something, so it's worrying that there is so little regulation of how much of the active ingredient is in the product and studies in the US recently found that didn't contain what they were supposed to and contained other ingredients that weren't listed on the label, many of which could actually be harmful (cheap fillers like rice, soy and nuts which could be deadly to people with allergies etc.)
It's a lot like the beauty industry and the crazy claims they can get away with about their products, preying on people's fears.
Banned? I don't think so, but I do think there should be regulations concerning what these 'miracle cures' claim to do. It's amazing how many products on the market simply don't deliver. I think consumers should educate themselves as well. There are two major reason bogus products exist - companies lie and consumers are dupes - at least it seems that way.