The reason casinos are not currently enabled is the fact the winnings cannot be properly detected by the server anti-cheat. Most servers with a decent anti-cheat will have the single-player poker machines disabled or they have a custom scripted feature (allowing you to use them), but you're given server-sided cash for your winnings instead of client-sided cash which is what you receive when you use them in single player.
Your wallet, bank balance. Is all server-sided cash, and has nothing to do with the client itself. When a player cheats themselves in any amount of cash, on 98% of servers they will get themselves instantly banned. As when the server anti-cheat runs its usual checks, the amount it has stored, and the amount it views in your cash-in-hand/wallet will differ. Resulting in being banned. Using the poker machines, etc, is client-sided cash. As soon as this is checked by the anti-cheat... boom.... you're banned.
