Just be aware and always read the ToS, casino nowadays are using this method to encourage user to deposit thinking that it will be just a regular deposit bonus. Always read the fine print.
Who has the luxury of time to read ToS, whether online or offline? I doubt a great number of people do read that, whether on casinos or banks. There's a good reason the ToS part is always written in tiny prints or it's too lengthy than necessary and that's to technically frustrate people from reading that part. That's what I think and it won't be far from it. I once had to close a bank account withing two days of opening because of it's ToS which the bank pointed out to me when I ran into a ditch with them. There was no way I could've seen that because it was almost like hidden. These guys know their deceit.
On the cashback thing; no one has to rely on that and think they can maximize that bonus. It's all hoax.