It has become a fashion like everyone want to have their own crypto hence why not a casino ? Being useful or convenient are not a constrain but I guess most gambling houses may come up with their own coins dedicated gamble with them. This fashion has already started with many crypto exchanges and it might be a time for casinos to copy that useless idea.
Basically I hate the idea of having numerous altcoins which are having repeated concepts backed and not having any value in rest of the world. As an innovation to have a common border-less momentary system, we have bitcoins but it seems we are again going back due to such purpose specific coins.
Maybe if they make up something that is special about it, like when you convert BTC to their specific token where they could use that only there and have some bonuses with it. I agree that it's somewhat useless, knowing that there's no reason to add it, only if like i said, the bonuses that could come with it.
It's definitely not a good thing to have so much alt coins, everything almost has the same technology in it and it's the applications that are the different but basically the same thing. I think there is more diversity with that compared to money in different countries. Some are going to be useless, some are going to stay, overall, no one could take bitcoin down.