%penetration items: Last Whisper and Void Staff

So the changes to Last Whisper this season was something everybody had been complaining about in the past several years from what I have read on the forums. It was something we as a community have wanted, now my question is will the same be done about void staff so that it's based off of bonus MR rather than overall? The way I see it is that mages or AP assassins are somewhat difficult to build against since their damage starts to spike so much earlier than your own magic defense can to match the damage they put out, what I mean is that when an enemy mage/AP assassin has a NLR compare to a Magic Null Mantle you're still going to be losing a chunk of HP and even in the case of vladmir top vs melee with hexdrinker you are still being hurt badly from his abilities without any AP to bolster the damage. I believe that there needs to be some re-adjustments to both offensive and defensive magic items this patch. Leave your comments down below and share your thoughts.