Why is the SKALE token an ERC777?

The decision to use ERC777 is due to the token’s unique locking abilities which was a requirement in order to facilitate delegation within the SKALE Network. There were no regrets with using this token standard, and the added benefit is that managing ownership over a delegator’s token was simplified. With ERC777, a delegated token never leaves the user’s wallet. It is simply locked from any further actions.
The locking feature of the ERC777 provided the flexibility necessary to work well within SKALE Manager, which consists of ~36 smart contracts including the SKALE Token, which all manage the flow of delegation, validator staking requirements, and SKALE Chain staking requirements involving the SKALE token.
More details about SKALE token can be found here: https://skale.network/token/