I voted only soft drugs should be legal, however I would be open to seeing why 4 people voted that all drugs should be legal.
My reasons for voting only soft drugs is because I've seen too many fall by the wayside, hooked on hard drugs that have destroyed their lives and the lives of those who love them.
Speaking for myself, the reason I voted for legalizing all drugs is that (1) it is manifestly unjust to criminalize what an informed, consenting adult would choose to put in their own bodies and a violation of their natural rights, (2) there is very little evidence to suggest that criminalization of hard drugs has done anything to reduce addiction rates, and, in fact, a lot of evidence to the contrary-- that before widespread criminalization of cocaine and heroin, use and addiction rates were much lower.
That being said, I recognize there is a compelling social interest in keeping addiction rates low. I would favor tight regulation of hard drugs-- limiting the suppliers and limiting the amount an individual consumer is allowed to buy from them, while harshly prosecuting black marketeers. This would reduce addiction, ODs, and use by children.
The other concern I would have about legalizing drugs is the effect it would have on certain cities and neighborhoods where the illicit drug economy is the only viable economy around-- things could potentially get much worse. I think legalization would need to be done in conjunction with other economic, social, and political reforms for it to be most effective and have fewer negative consequences.