It depends on the specific casino, of course. They are not all the same (in terms of interaction with users). In general, any bonuses are good by themselves. Some even provide free bonuses, such as freebonus.co. So, what's your question about? Do you blame casinos that their rewards are not forever? What do you think a casino is? It's not a charity organization, they need you to get involved and spend money on their website. That's the point of good welcome bonuses. If you want to abuse the system, you can change casinos, getting every time good deposit bonuses.