I honestly fine if KYC is needed on exchange. Because i think it's gonna be safe if it's on big exchange like binance, but there's no guaranteed for that. also KYC can help when your account hacked or even the exchange get hacked like what just happen lately with kucoin. if this happen what they can do is lock your account or the balance, and when you want to claim it back you need to give new KYC that matched with prevous KYC. but i do not want KYC on Bounty or ICO.
Echanges dont need your KYC data. If they lock your account you can send them a prove that you are the holder of all the addresses which you have deposit from or withdrawal to it. Just sign few of those bitcoin addresses which you have used before. That is prove enough.