Seen from another point of view, if I only pay 0.25% to buy and sell on a centralized exchange, why would I pay more on a decentralized exchange?

Certainly many will do that. However, some do object to KYC while others find the centralized exchanges difficult to get listed upon. Binance just make some news stating that it is going to drop tokens without a great deal of activity.

I agree, once the insanity of DeFi diminishes, we will see legitimate use cases emerging.