Well you can't have fedipool without StratumV2 so the latter is a must. fedipool helps further decentralize pools. Even with V2 a pool could technically reject the block sent by miners and use their own( I think), Fedipool would spread that responsiblity onto multiple guardians (essentially many pool operators) which should reduce the risk.
Please being ecash adds privacy to a miner's payouts. It's an interesting concept.