More Magic Pen Items?

I feel like this is somewhat self explanatory but I was hoping to get Riot's opinion on this, with tanks coming back into the meta and getting more items that they become unkillable late game mages are stuck using abilities on tanks and not even denting them. I feel like the main issue is that there are not alot of magic pen items. There are 4 magic pen items on summoners rift: Sorcerer's Shoes, Liandry's Torment, Void Staff, and abyssal Mask. Abyssal Mask does give AP so I usually dont build it, but going up against tanks like maokai, or cho gath who either have too much health for a mage to do damage or too much sustain mages cant do alot against them. I was hoping that in the next few updates Riot implements a new item for mages that grants AP AND magic pen. If you look at Attack Damage based champions there are several options for dealing with tanks, you have Lord Dominicks or Mortal Reminder which grants %armor pen, they have lethality, and items such as bloodrazor or even bork. Mages dont have this option and while 1 shooting the adc is fun.... being able to dent the super tanks would make mages a lot more useful especially becuase against a team with 3 tanks mages aren't very useful. They cant get to the ADC because they have tanks to peel and Magic Pen is very limited. My idea is to either implement more Magic Pen items, or an item that turns a % of damage dealt into true damage or to have an item that gives %hp damage somehow. I'm not sure my ideas are the answer but I just wanted to get Riot's opinion on this issue