Straight to the point - I believe League is long overdue for an item that deals bonus damage to shields. The fact is, shields in League are absurdly good, especially when stacked. Not to mention, shields are even better on champs who are tanky.
Sure, you can argue that mass shielding is just an edge case. You could also claim that shields have the counterplay of forcing players to "time" it correctly, rewarding skill for players who anticipate incoming damage. Of course, you can throw all of that out of the window when you can just dump all of your shields onto a prime target in a fight, and then watch in awe as the shielded person takes little to no damage with their excessive shields soaking up everything.
I think shields have built up some power creep over time. Just saying. There is a reason why a certain champ who rhymes with pharma gets picked so often at competitive play. Cough. Cough. We also cannot forget another one who rhymes with ruru.