they could be doing it for security, money laundering is a major risk and I believe every other exchanges have been fighting against money laundering, including kucoin, nothing to worry about if you're not doing anything illegal - kyc got some benefits as well, you can use that for your advantage
I do not have an actual need for large numbers or transactions, as you can see in one month for example I only had 9 deposits and 4 withdrawals, those "extra" benefits are of no use to someone at my scale.