Why do we find it acceptable to help...

I think if the widely available help for alcoholics, smokers, or opioid addicts mainly mitigated the negative consequences - enabling them to drink, smoke, or dope more - it wouldn't be nearly as acceptable.

I personally expect weight loss medication that simply makes people want to eat less will reach cultural acceptance.

Case in point, cigarettes have been known to suppress appetite for ages, and people have elected to smoke to help stay thin for decades. There was never any crushing social stigma attached to doing this as a weight loss strategy (that I know of).