Nothing nefarious about it. Many of the same folks who lobbied hand over fist for this revenue model quoting the "game experience may change at any time" part of the TOC, just learned what that means.
After people paid to attain faster for two rounds of character power, the second one gets rolled back equal to the first one - something they also paid to attain faster previously. The grown adult customer feedback from people who paid is they didnt need to pay for another equal item set, and had they known it would get nerfed to equal they would have just held on to the first item set and not paid to attain the second much more quickly. The company made those more recent ones temporarily better which caused people to pay to attain those more rapidly, only to make it equal to the first ones.
When your revenue model is players paying to attain character power faster, you can take the normal amount of rage you would see over a nerf and multiply it by 10.
No one is claiming the sky is falling. If it was they'd find a way to charge us AS to keep it from doing so.