We don't need this many but how can you stop people from wanting a piece of the crypto exchange money making machine? It a like the sport betting sites do we realy need 1000s of them? Off not but that won't stop new ones from starting.
it is not just about money grabbing, but mainly because the existing centralized exchanges all have big flaws in their design that doesn't satisfy the needs of the cryptocurrency market traders so new ones are created to attempt at filling that gap but eventually they either don't gain enough traction or if they become big (like binance) they turn into the same flawed thing.
for example KYC is one of the worst things in altcoin exchanges. new ones come alone without needing KYC at first, they become big then they enforce it!
They have to enforce KYC if they want to run legitimate business. Thee are strict legal rules when and why you have to implement KYC rules into your business. I guess no one wants to risk big punishment or closing the business because they are not complied with the law and actually I wouldn't like to do business with such exchange.