Hydraulic systems can have issues with long term operations in a vacuum, so going all-electrical offers reliability and simplicity benefits for long operations

Hydraulic systems can have issues with long term operations in a vacuum, so going all-electrical offers reliability and simplicity benefits for long operations in space. It's also considerably easier to make electrical systems with redundant power supply than it is to make redundant hydraulic systems, especially given the tight volume and mass limits of space travel.