It's actually quite simple, as prohibition in the US proved. They made alcohol illegal, and the mafia and bootleggers blossomed and became rich and powerful. They made it legal again and they moved on to other illegal stuff, because there was no longer any profit in alcohol. When it is legal, you can regulate it and tax it. When it is illegal you cannot. So, like most things, it gets down to the overriding principle, it is always all about the money. Sometimes it takes the government a while to get a clue.