I did wonder about that, not sure what the loads are on these thing, but I do note that the main traveller movements don't look smooth in all cases as if the load is holding them in place a bit.The problem with the orange is that when the jib sheet is anywhere but dead central and aligned with the orange it will torque the car on the tracks and jam.
They could maybe do a more elaborate job with the tracks to resit that torque. But you'd have to weight up the weight and friction of more sets of bearing / rollers versus this set up.
I sailed a merlin this weekend which is a 3D jib angle adjuster (not self tacking). But one problem with the system was that it twisted and became hard to move using only a central puller.
So the hydraulics could just be for smooth movement. But no-one else seems to have a problem, and although Ineos are moving the sheet angle, they have 2 tracks which I would have expected would reduce the risk of jamming more than adjusting the sheet angle is increasing (basing that on no more than engineering hunch)