Why would you even play at such a casino?
Most of us if not all prefer instant withdrawal ofcourse. But there are still some online casinos that manually process their users withdrawal. Playing in on an online casino is matter of trust, i would rather play on one that manually process withdrawal but im sure that my withdrawal will push through.
What if they tell you it's manual but really have not enough money to process instant withdrawals and have to delay them? You can never be sure if they are telling the truth. I feel like delays are shady and I wouldn't do it. Mtgox was delaying withdrawals before the collapse because they were insolvent.
If all industry is going with instant withdrawals and you are one casino that is delaying you are going to lose customers.