I don't think it is a big problem to have some advertising of bookies during some sport matches. The problem (in my opinion) is the quantity and how often those advertisements are showed to people watching the match, who may find them annoying and uninteresting on the first place.

At this pace, sport matches are going to become more like a event for casinos and bookies to show off their services, instead a event for people to get excited about their favorite team facing an opponent, and share emotions with the rest of the fans attending to the match.

It is about money, that is obvious, ads are a way to fund sports and leagues, so instead of getting rid of them. It would be enough with limiting the time on screen those ads are allowed to occupy.