A reader makes a fascinating point:
You ask "Does the formerly compulsive gambler Bennett recognize any distinction between pleasure and medicine and ... hedonism?"
Actually, a compulsive, addictive personality would likely have great trouble making this distinction. You and I could go on a vacation to Las Vegas, plan on risking an amount of money that is reasonable to us, and on this trip we may win but we would more likely lose. However, we would be able to have a good time during our mildly risky behavior. Bennett, as an addict, cannot do this.
If he went to Las Vegas planning to risk a certain amount, he would be very tempted to risk more, and more, and more until it was a truly destructive amount for him to lose. In his psyche, it really is either no dabbling in slightly harmful fun at all, or complete hedonism. Similarly, he may not comprehend the idea of recreational pot use at all. For him it is no acceptable use, or addiction. Now the question he should ask himself is how much he should weigh his own experience on such an issue. After all, if we only thought in terms of addicts, alcohol prohibition would come back.
The even bigger problem with his argument, however, is the assumption that Weeds could not have been on TV in the past. Was not The Godfather saga one of the most popular and the most critically acclaimed movie series of all time? People were certainly emotionally invested in the success of the Corleone family watching those movies. Does this mean that the 1970's households were constantly cheering for the Mafia to beat out police in their home towns?
The better explanation is that television and movie viewers have always been willing to accept non-traditional protagonists if the story is well constructed enough.