If you want to nerf long-standing, widely used armor sets, fine.
But if you're taking things from players, you need to compensate them for their loss. At least give every player who uses a nerfed set its cost in upgrade materials plus an allowance for the time it takes to acquire it.
As it stands the entire cost of change is born by players. There needs to be some friction in place for the developers. It has to cost the developers something, other than their time for which they draw a salary from, for taking things from players.
Just two weeks ago you offered Seventh Legion rings on the gold vendor knowing they'd be rendered useless. At least offer refunds for those.