If we regulated every thing that made false claims or other, nothing would be on the market.
Sure they might not be an effective quitting tool for everybody, but neither is pretty much any quitting tool. Should everything designed for that purpose be banned unless it proves 100% effective? Some people find them useful for situations where they can't smoke, some use them to help cut down, some manage to quit.
It's like any alternative product, go in to Holland and Barret and look at the array of pills and potions which all claim to do something or other and have been proven to be little more than snake oil. Anyone who buys them without doing their own research, has only themselves to blame for wasting their money.
As for the "oooh, think of the children" line, this winds me up something chronic. If a child is buying these things off the internet, then the parents deserve a slap. There are much worse things a child can buy off the internet, parental controls are vital.
I would also question whether e-cigarettes are harmful to children? And if a child is buying them, aren't they just as likely to be buying the real thing too?