Is the AD really what attracts people to rush Essence Reaver though? Shouldn't you be messing with the CDR or the mana restore mechanic instead?
The CDR and the mana restore are both functioning competently, and they would be hard to adjust in small increments. We don't have to target them just out of principle. The AD is just as important to the item's functionality, and it is too low for the item to do its job. The item can get low amounts of AD as a small improvement, and there is nothing wrong with that.
Also, have you considered that maybe the Ghostblade rush is stronger, not because the item is better but because the component is better?
Both are true. Ghostblade is a superior item when it is completed, and it has a better buildup. It has everything going for it but 4-6 item scaling. That justifies a nerf, and the item's cost-efficiency when completed is a perfectly reasonable target.