I do not see the really problem about this. Why should it be a problem to give personal details, if there is nothing to hide? For sure they will not share any information with others.
Most gamble sites do not publish the KYC on their site, and when you win much money they will always ask it as well. So then it is much better to state this KYC in the terms. Only good.
Only good thing is that they run this site with a valid license. We saw many unlicensed casino's the last time.
Its all about personal preferences obviously. In this case you think that it is not a big deal to do KYC but it is a big deal for some other users including me. There are still many people want to gamble anonymously especially in bitcoin/crypto gambling sites. I myself prefer not to send my personal details for my gambling activities so I will always look for gambling site with no KYC. In case of a big win, it depends on how big the win is because value is something subjective.
KYC and sharing of your customer details defies the purpose of crypto built casinos. Most people want to remain anonymous. There might be many reasons why people prefer to remain anonymous but with so much increased risk to malicious activity one can't be too prudent in maintaining their personal details secure, and anonymous. As for the wins, I agree what's called 'big win' is subjective and even in these circumstances you could get away with publishing the user's username and still keep personal details offline.