Why is Riot So Afraid of "Melee Only" Items?

Put simply, a number of items (Blade of the Ruined King, Iceborn Gauntlet, the new Trinity Force, etc...) in the hands of attack damage carries are blatantly imbalanced. Why then is Riot so afraid of making these items, or at the very least, components of these items applicable only to melee champions? This seems like a much better solution than simply knee-jerk nerfing the item as a whole which in fact does little to affect the ranged carry but heavily affects all of the other classes that make use of the item.