Pro-regulatory statists, ignorance and the FDA are to blame for this ban.
Organizations which are "consumer watch groups" tend to be very pro-regulation for whatever issue they target. They froth at the mouth to have laws banning or regulating this and that. They hate the idea that you and I may choose something that they disagree with. They are a vocal group that is more of a threat to freedom than any terrorist group today. People take notice when a group tries to kill you, you and your neighbor will take up arms if necessary to protect life and property. People tend to be lulled to sleep by the promise of "public safety" or "protecting the innocent", and willingly bend over and spread em.
Ignorance of the masses makes it easy for the above crowd to accomplish their goals. The parents of people who have died from Ephedra, instead of accepting that their child died from misuse of a product or confounding factors, want someone to blame. They easily blind themselves to the reality that their child had pre-existing heart disease, took excessive amounts, or took other drugs together, in order to find the culprit of their childs death. Their constant pleas on TV to ban the drug that took their child from them is like gold to legislators who wish to control the industry.
The FDA wants to regain its lost powers. Prior to the DSHEA bill, the industry had to prove safety and efficacy before it could market a product. FDA regulations require many millions of dollars of testing to be done in order to accomplish this and few companies have this amount of money to invest in something that may fail FDA scrutiny. Thus prior to DSHEA, we had next to nothing in the supplement industry, some vitamin C (no greater than 500mg/tab), B Complex and ginseng.
The DSHEA bill made the FDA prove a danger before it could ban or regulate any natural product. This paved the way for numerous products which would never have been allowed before. Even with little regulation, the supplement industry still boasts a respectable safety record.
The FDA hates the DSHEA bill and wants it repealed. The consumer is to stupid to be allowed to purchase what he wants.