I wouldn't mind submitting my KYC in the beginning before making deposits, as far as I know that the casino is reputable. I also think that the reason why some casinos don't ask for KYC in the beginning is to encourage more gamblers to gamble in their casinos, the easier the process to get in the more customers they'll get because it's not every gambler that can be willing to submit KYC unless it becomes necessary to collect their wins. I believe that the reason why casinos even requires KYC is because of government, I don't think that they'll bother about KYC.
If that casino have a good reputation, we don't have to worry to submitting KYC to them because we believe that they can take care of our document with right. They will protect our identity from any bad things that can occur so they will gives secure to their members that they are in the right hands.
By doing KYC, casino will knows their customer and will lets them to deposit or withdraw money in a huge amount because casino will check every document before they approve their submission. Their members will finds more benefits by becoming verified members on the casino because sometimes, casino gives something to their verified and loyal members to appreciate what they did to casino. But that will depends on every gamblers because some gamblers doesn't wants to do KYC process because they thinks that they only use gambling as for fun so they don't thinks that doing KYC is important for them.