I'd concur with pretty much all of the above.
It's definitely very VERY cost prohibitive to setup. Which would be fine, if the products it made sold like hotcakes.
The supply/demand issue. A great many players seem to find the negative coded/scripted effects of addiction and withdrawal not very entertaining. This has been brought up recently elsewhere too. Like that drugs could use some love in the RP/echo/effect department to make them more appealing in general.
I think they'd benefit from some 'positive echos' or some kind of inner RP guidance script that tells you how amazeballs you feel right now. "you feel so goddamn fucking good right now, you start tripping balls man..wait did you see that??" etc.
I also think they'd benefit from being less rigid in how they cause to you react when you're withdrawing. I realize drugs make you not act like yourself, but it can be kind of redundant and repetitive to RP the scripts if you consent to play an addict. It should still be bad, you're an addict! I would not advocate softening the blow. But I think it could be made more amusing and flexible to RP the junkie.
The symptoms (nosebleeds, twitching, itching, shaking, drooling, sweating, aggression, confusion, etc) could probably be expressed in smoother ways that are more adaptable and less 'scripty' Some of them are totally good already, nothing wrong with just having an abrupt nosebleed, it just doesn't need to be so firmly set and detailed in how some are described. It's plenty awkward to have your limbs just suddenly start shaking and your face flush out or sweat starts pouring from your face.
An example of what I mean would be like.. having a period where every time you try to talk you do that *wheeze* thing. It clears up eventually, but it's set on a random timer, so you don't have the ability to just sit and wait for the script to run down or do that.. oh shit I feel a slap coming on *runs to other room* (which happens and makes things a little awkward..)
It's also flexible in that you're made to have a negative effect that you can't hide, but you can play it however you want, "uhh I need to work out more, *wheeze, twitch*... Fuck off okay, *wheeze twitch* do you have any dez on you?"
Or in the case of forced actions, instead of just having a canned script that runs and dictates you preform the same action every time, in exactly the same way (you say "exactly this exact thing" you slap 'nearest-guy' and give 'all-money' to 'nearest guy' etc.) some kind of inner thought for a cue, immediately followed by JUST the negative action, might be cleaner for RP.
You think: all these fucking people are tools, fuck 'nearest-guy'. do you see how 'nearest-guy is looking at you right now?
You feel so pissed off right now.
nearest guy: "HEY!? What the hell!"
"..I.. actually.. shit, sorry. Hrnng... I should go, sorry. Fuck. ARGH! Fuck."
"Fuck you! And you! And especially YOU! I am done with you people!"
"...Don't act like you don't know!" *cries* *runs away*
You think: "Did 'nearest-guy just put a pill pack in his pocket? He's got the goods!"
*steal (endo) from *
nearest guy: "What the fucking fuck man?"
"Uhh I thought I saw a roach on your jacket.."
"..Give me the fucking endo you asshole! I know you have it!"
"Shit man.. tweaking really fucking hard.. I thought you were holding.. my bad."
Basically, a less structured/scripty method of making you you act like you have a serious problem, but leaving more freedom to determine why your characters junkie brain decided to be slapping and spitting, with inner cues to help you determine those reasons in a pinch. If you're playing a sobby type you can start to sob, If you're playing the angry type you can shout fuck all of you!! etc.
You also have some less awkward options to play off what just happened in the self-justifying, excuse-making, evasive way that junkies do, instead waiting for a script to run down.
Those are my thoughts anyway.