Here I agree with you, the volumes on decentralized exchanges are much smaller, although I like them more because of their anonymity.
I agree with you that decentralize exchanges do not have a KYC procedures, but there is no margin trade on decentralize exchanges.
I think that traders and investors must have a choice on what exchange to trade. That is why it is important to have listing on decentralize and centralize exchanges.
That's for sure, there should be such a choice, because users are divided into two categories, some do not want to go through the KYC procedure and are used by decentralized exchanges, while the security of funds is more important to others and they use centralized exchanges.
Many traders use margine trade. It allows to earn more money. And margine trade is possible only on centralize exchange.