Seriously, I think it would be a REALLY bad idea to legalise all drugs - I mean humanity is irresponsible by nature. Also introducting heroin/crack etc. into tobacconists would allow more of it to be accessable to the public.

Consider:
David comes in to school: "Hey guys my dad and mum were doing this drug they bought in the local shop last night [lets say heroin], I took some, dudes, it was the most amazing thing I've ever done! I mean if mum and dad are doing it can't be that bad can it?"
In the kid's psychology his parents are both doing it, so why shouldn't he? Let's not go into educating children that it's bad to take this kind of drugs - because that would result in their COMPLETE distrust in the system if over 18's are able to get it.
And there you have it; a couple of people in David's year follow suit, bearing mind that it would be VERY easy to get your hands on heroin if it was sold in shops, and there you go - youve got a lot of people addicted to heroin.

And don't tell me that it's harder to get if its regulated - tobacco is regulated - and look how many kids smoke, i daresay half you use tobacco in your joints and your not 16/18 (depending on the country). Also you'd probably see a lot of dealing to kids, who simply buy from the local shop and resell to children.

And PLEASE: lets not go into the effectiveness of health warnings here, people - Imagine "Warning Heroin/crack/meth etc. may be harmful to your mental and physcial health - only over 18's should do this drug" . AS IF kids are going to listen to that when cigerettes are more harmful and they STILL don't, including adults + these drugs are some of the mose pleasurable experiences known to man, pretty tempting for a kid to ignore those warning - tobacco isnt.

However: I am FULLY for the legalisation of Cannabis, shrooms and a few others.