Effective arbitrage is required for efficient markets. Again I'll repeat: the sheer fact that this is all decentralized/identity-less is already a novel aspect.

The specific DAO's I linked to build products that allow for shared arbitrage profits and an autonomous decentralized stablecoin respectively- the utility is found in the effective distributed markets they help optimize.

The very fact that you can trade coins or earn interest on a loan in a decentralized manner is the utility. Composable financial legos are pretty useful.