Well just in my opinion, every casino has their own budget and the bigger the bonuses, also bigger chance of players winning bigger amounts or abusing bonuses. I don't think that casinos have limitless amount of funds they can just give as bonuses that's why they don't REMOVED.
It depends on what casino is it, what casino do you play? Now I am little addicted to <snipped affiliate link> cuz I am absolutely glad to play it. Bonuses are alright, more often than not I get cash.