Pounding - I totally agree that "we need a grown up discussion on drugs". The problem is that there is crushing political pressure on one side and ignorance coupled with prejudice on the other. Politicians don't want to be the one to say that actually drugs are not all that bad and people who have been brainwashed all their lives about how all drugs are horrible and that's why they are illegal don't want to hear facts to the contrary, let alone have that grown up discussion.
"I meet countless addicts who think nothing of burgling an old lady and pushing her over in order to fund their next hit... I also come across people who have no dealings with criminality whatsoever other than trying to buy some pills or cocaine on a night out. People who hold down decent jobs, contribute to charity, have functioning families, etc... it seems ludicrous that we are putting them in the same categories"
Very true, and that is because "drugs" is so broad a category as to be meaningless. The addicts who hurt old ladies to get money for their next hit are not doing it for an E or LSD. Nowhere in the world has anyone prostituted themselves for a tab of acid or a joint. There is a world of difference between heroin & crystal meth, and recreational drugs like MDMA & LSD.
"The one thing both groups share in common is that they encourage the growth of organised crime by buying the drugs."
YABU to leave the responsibility for organised crime at the feet of the users, while it belongs solely in the hands of legislators. There is clearly (a lot of) demand for these products. Whose fault it is that they are not sold by legal organisations, quality-controlled, and taxes received by proper authorities? Not the users'.
"while they're illegal, anyone taking them is contributing to that seedy underbelly whether they like it or not. I have more time for recreational drug users who put their money where their mouth is and actually campaign for legalisation which could remove some of these issues."
Don't hold your breath for that. In the real world, (1) Nobody has time for that sort of thing, and (2) Nobody will put their neck out and clearly show their employers, parents, etc that they use drugs by campaigning for legalisation although it is nobody's business what they do in their spare time and with their own bodies.
"the sort who think that the rules apply to everyone bar them"
Yep, that's me. When the rules are dumb, I don't feel like following them. Millions of others clearly agree.
What I eat, drink, smoke, or otherwise ingest into or do to my own body is nobody's business. I didn't listen to my mum who said I should stay a virgin until marriage and no, I certainly didn't listen to government authorities who say I couldn't smoke or eat what I wanted to. They can all bite me 
And if I lived in Northern Ireland, I would not have had an unwanted child just because the rules there say I should. I would have found an illegal, criminal organisation to provide the illegal abortion I needed.