I think it's a mistake to be completely cynical about the motivations for the war on drugs. A lot of the lobby groups that now seek to perpetuate it were in fact created by it (e.g. the prison lobby). The problem is that it was a kneejerk reactiom to a real problem (addiction) that simply had massive unintended consequences, including the creation of cynical interest groups.

I think that when arguing for drug liberalization one should acknowledge the validity of the concerns of those who have heartfelt support for drug laws. The point isn't that addiction isn't a problem, it's that criminalization doesn't fix it.