I agree that it shouldn't be socially acceptable, and any population that sees an ad like that should be very willing to never buy from that company again. Then the action they took wasn't a big enough deal. Eventually people will stop when the lotto goes too far. As well, lotto companies should be well regulated, and I think that F2P games should fall under similar regulation. However, those regulations should be explicitly things like requiring multiple confirmations, informing users about the harms of gambling addictions, how to avoid them, and so on. Not regulations on how much people can play, or if gambling is legal in X situation. Yet with lottery, I wonder how many people would condemn the ad but be unable to stop. Not even the type of person we think of as addicted, but just your "regular" person who when leaving the grocery store starts to think well what if this time I would have won.
I don't have a source to back this up directly at the moment, so I'll get back to you, but there's a similar issue in the mobile and F2P gaming department where almost the entire industry is propped up by an incredibly small group of mostly disadvantaged, and (if I'm recalling the article correctly) addiction-prone personalities. Nobody talks about the very real issue of preying on these people through literal psychological gaming, because fixing the problem would cause the entire market to implode under the weight of its own instability. I'm not saying it's useful as a direct analogy to the lottery system, but I find it curious how many systems we put in place societally that we know are intrinsically abusive but don't give enough of a shit about to fix on a fundamental level.
I wonder what "too far" would be though. I think as long as they did it in slow easily digestible pieces, they could go very far. There just has to be a scapegoat so people can tell themselves it's not messed up. I mean we are all in agreement that the billboard was bad but I'm sure plenty of people would just laugh at it. Then there's the fact that if others started boycotting people are more inclined to say well my odds of winning are higher now. They shouldn't...but they will. Then the action they took wasn't a big enough deal. Eventually people will stop when the lotto goes too far.