I've been a while since the change.
I've done some testing with the item, and it still feels like the nerf was uncalled for. The reason AP champions have declined is purely due to both their unimpressive itemization, and the AD's new and better itemization.
With AP champions leaving something to be desired, I think it's time the Athenes nerf and the Deathcap nerf were both rolled back. It would be a step in the right direction to getting AP mages back up to where they need to be.