This can be seen the other way around.
Doing it that way you could say that all the people making an item after the nerf, because it would be a nerf, are at disadvantages.
This could also be seen as a : Make the strong/rich stronger/richer. Because usually the stronger player or richer player are the first ones to make item/content. And in this case, the other player would be at disadvantage even more, and the gap wider.
There is sadly no easy answer, and we are trying to do our best to satisfy every type of player. We understand the frustration, and hopefully it won't happen again. But I am sure this change is for the best, and had to be out as soon as we could.