Vanishingly few people succeed in exercising discipline and self-control long term. But obesity is caused by food addiction and the idea is once you've kicked the addiction and got over the withdrawal etc then it's gone and you no longer have to fight it. I don't "exercise discipline" to stay thin. I just don't eat copious amounts of junk food because I'm not addicted to it.
So if the drugs are used to soften the withdrawal symptoms such that people can learn to like real food and kick the addictive crap then that's good. But if they're used as a magic pill with no other lifestyle changes then I'm sure people will just go back to what they were doing before once those pangs come back.
I'd still rather we went after the industry peddling the addictive shit. We went after the cigarette companies. But food companies seem untouchable.