The advantage mechanic was developed specifically to avoid having the modifier stacking that got out of control in 3.X (including Pathfinder), so I'd rather it give advantage than for it add a modifier.
While that might be true of the Advantage mechanic, I doubt the point of Advantage is to give it out in a very simple mechanic afforded by High Ground now.
Regardless, there is a giant thread about this very subject. Still hope Larian sees the wisdom of why WotC didn't do this with DnD 5E along with their recent changes of removing Backstab for everyone and food no longer heals but instead is a management tool gives me hope that they seem to agree on this same subject.
