Placing ban on casinos can be one of those decisions made depending on the context of the country and goal of government. Two views can be considered
Firstly, bans make sense when gambling is becoming a source of widespread of social vices ranging from addiction, crime, or maybe financial ruin for vulnerable persons. Governments can intervene when cost to society over burdens the federal or state revenue or value on entertainment. Though certain federations with strong religious and/or moral values can place bans on casinos standing on cultural or ethical reasons.
Finally, placing a ban on casinos may not automatically solve those problems, because people can switch to online or underground gambling, which can be hard to monitor or regulate and more dangerous. Governments can tax, monitor and create opportunities for jobs and tourism from legal casinos. Instead of a complete ban, certain federations focus on strong regulation like age limits, time spent on it, support for addicts with tight monitoring.
If they don't intend to create more problems than they wish to solve, they can consider having a solid plan on how to handle illegal gambling, revenue lost and public demand when thinking of a ban