Mempools are brilliant for censorship resistance. They're also critical to:

• Miner decentralization - keeping transactions in a publicly available mempools makes it easier for smaller miners/pools to participate.
• Layer two contracts, i.e. lightning nodes need accurate feerate estimation in order to broadcast reliable, time sensitive transactions.
• Protocol reliability. The alternative, centralizing around a singular block template creator creates fragility in the network.

IMO, mempools are highly underappreciated for all the benefits they bring.