Pictures of boobs being readily available doesn't change their popularity. Advertisement is about getting someone to pay attention to what you're selling, or in the case of these shitty beer companies it's getting people to think about their product as they were already going to buy some form of shitty beer. Boobs do that. Maybe not for everyone but the majority of men who see a picture like that and look at it, they will pay attention to the ad. Seeing as how the majority of beer drinkers are men....