Why is MeV a problem?

Could you please elaborate on why MeV, or miner extractable value, poses a significant issue in the cryptocurrency space? How does it threaten the integrity and security of blockchain networks? What are the potential consequences of miners exploiting this value, and what measures can be taken to mitigate these risks? It's crucial to understand the intricacies of this phenomenon to ensure the sustainability and trustworthiness of decentralized finance.