Promoting gambling shouldn't be considered a bad thing because you aren't forcing anyone to gamble but only promoting it. How many times has an advertisement being called bad because they're doing a promotion that can has addictions. Gambling is for fun and they're promoting for people to come and have fun.
It's bad for some because a promotion like that is very subjective.
You cannot please people just to say that you're advertising a casino or gambling and you're not forcing them to do so.
There's no difference from advertising it and convincing them to try it. And that's why you can't blame the others for thinking that it's a bad thing whenever they see one do it.