Apart from requiring publish permissions to perform these actions, there might be reasons within organisations to allow publish, but not scheduling of the same actions. I can't actually think of a practical example where this might apply though, publish and scheduling are fairly similar in terms of organisational roles. Maybe it's a non-issue?
I think it's worthwhile. I could potentially also see a desire for separate permissions for adding and removing. Maybe anyone can add an embargo date, but only certainly people are able to cancel it (or vise versa).
Apart from requiring publish permissions to perform these actions, there might be reasons within organisations to allow publish, but not scheduling of the same actions. I can't actually think of a practical example where this might apply though, publish and scheduling are fairly similar in terms of organisational roles. Maybe it's a non-issue?