Even when getting 15 free spins you have to make a deposit to claim it there is no way to have fun 
Any casino security system is unable to detect greedy people. If the bonus can be withdrawn without the requirement, then people will create as many accounts as possible just to claim bonuses, don't really want to enjoy gambling.
Now that it is a obligatory before withdrawing their funds (Like me actually lol) now i got deposited a minimum deposit and wagered (luckily i won lol) and now i have withdrawn all my funds inside their site.