Good answers!
Mushrooms were legal in my country only until recently, and the major reason they banned them was that a French tourist girl, who was very troubled already (i.e. psychiatric case) jumped off a bridge while tripping. Yes tripping can push people over the edge, which is why you should not trip while close to an edge (literal or figuratively speaking). Thinking you can fly off a building is most often not the danger, what is dangerous is precipitating the problems you have already. Of course, the mother was in rage and she took French politics with her. Incident politics don't mind the countless times mushrooms are taken without something tragic happening, they only see the rare occasions.
A panel of researchers were instituted to find out the harm potential of mushrooms and they found none. The stubborn minister decided to ban them anyway. Politicians are sadly often total pussies who blow with the wind (emphasis on blow). Subsequently mushroom fruitbodies were banned, saying nothing about the sclerotia (magic truffles / philosophers stones). Since the ban diverted the attention, nobody really cares about the legality of the truffles until one ignorant and severely deluded tourist will come along one day to abuse them and have an incident... raising hell once again.
So you see, it's better to actually trust research and common sense than the legislature decisions of some people under pressure who absolutely don't know the first thing about the subject! Here in the Netherlands politicians tend to be pussies, easily pressured by politics of larger countries. But US politicians may be worse in some occasions when they want to prove a point, deciding on matters like this as part of a campaign.
Yes, psychedelics are less predictable than alcohol and cigarettes and things like that (many of which are certainly bad for your health), the dynamics are probably that very few people use them because of this (it never really spreads like the use or abuse of a hedonistic drug like mephedrone) or maybe only in a subculture. Since there are not many who use them and support them, or even know what they are all about... the majority is left ignorant and afraid of what they don't know. Mostly guided by things like the media which work extremely similar to incident politics, and anti-drug propaganda. This combination of factors makes the whole case lopsided which does not even allow much room to better through education and information. It is self-sustaining but proven to be ineffective at repressing the part of the population that DOES use psychedelics.
Tobacco has been under heavy fire for a while now, and the societal problems of alcohol also seem to be getting quite some attention but a major reason not to ban them is that the use is so deeply confused into our culture and the countless people that use them (not to mention the money governments make from the taxes... though this is probably compensated again by problems that are caused). Psychedelics and the more obscure classes of drugs are much more easily banned. There is little resistance! Who will speak up for them? I think that it's important that less people use them otherwise the illegalization might be a different story.
Also, if alcohol and tobacco sale is illegalized people would probably still get them from somewhere and harm themselves and others with them but the government would not get the income from them, criminals would.
Mushrooms can have a profound effect not as a drug but as an experience in your life. It can be very impressive in both negative and positive ways and you may carry this with you. Some say lessons are learned in trips (I would) and they can be harsh lessons. Golden rules of set & setting should be taken into consideration to make the outcome as positive as possible, though you cannot know all the factors so it leaves a part of uncertainty. It is best to fill in this part with trust that everything will be okay.
Marijuana does not have such a deep impact acutely but unlike mushrooms it can be psychologically addictive and it has been for me for years (I quit about 2-3 years ago). It made me lazy and altered the way I thought (made it more fuzzy, neutralized things as well in a bad way). Ultimately it was the mental fog that made me stop because I was fed up with it. When taken in moderation there is not much of a problem at all with marijuana.
