I can respect some casino who adding required KYC before using their service. most likely about money laundry and legality for their customer. as we know some casino restricted some area for using their services. they didnt want their legality had problem because they didnt even know who using their service before hand . and also KYC in most gambling platform only formalities and they wont making harder registration for their new user.
I mean that would be the least that you can do when you are doing business, complying with the rules and laws that govern your business. I like the idea of KYC because it helps you not become a suspect of something bad in the casino because you know that you won't do wrong because they have your identification.
but doing KYC also means that you are now publicly known and you are no longer unknown or anonymous. If you win a huge amount and you don't want to inform your local authorities then the casino will do that for you and you will be forced to pay taxes.
I think the idea of KYC should be forced to players who are cheaters or in some way are believed to be connected with money laundering or have cheated the gambling site in any way possible. Without a strong reason KYC should not be done.