Why Riot doesn't make Iceborn Gauntlet's Spellblade do magic damage?

Yes, I know that most Spellblade procs (Lich Bane, Runeglaive enchantments) already do magic damage.

However, the problem currently with Iceborn Gauntlet, is that it is outclassed and there isn't really a lot of reason to use it over Trinity Force or Frozen Heart on champion where you want to buy it. Iceborn Gauntlet does less damage than Trinity Force and doesn't give many important stats (such as attack speed and AD), and offers less armor and less cooldown reduction than Frozen Heart while only offering slighty more mana.

You think that it could replace both Triforce and Frozen Heart on a build and save a slot, but you are really better off just using both items in a build because their stats are just superior to Iceborn Gauntlet. And, in a meta where everything has a dash, you are better off using Trinity Force's movement speed steroid instead of Iceborn Gauntlet's slow.

An idea to give Iceborn Gauntlet a more estabilished niche over Trinity Force:

> Unique – Spellblade: After using an ability, your next basic attack deals 125% base AD bonus physical damage to surrounding enemies and creates a field for 2 seconds that slows enemies inside by 30% (1.5 second cooldown).

Change the "125% base AD bonus physical damage" to "125% base AD bonus magic damage". In which way this would give a more estabilished niche over Trinity Force? Well, because then even if it would technically still do less damage than Trinity Force, this item would do a different type of damage, allowing it to work well against tankier bruisers that would itemize for armor. Also, most champions which would want to use it are tanks which do mostly magic damage with their kits and do not really care for the attack speed from Trinity Force. Examples being Malphite, Maokai, Sion, Taric (if you are, for some reason, using him top), and Ekko (when build as a Cinderhulk tank in the jungle). With Iceborn Gauntlet doing magic damage, they could go with an AP bruiser build combining magic penetration items, and it would still be a very tanky build. The synergy with Liandry's for example, would be fantastic.

Also, this would allow Iceborn Gauntlet to actually serve as a cheap, alternative item for champions that use Trinity Force when they are behind or when they really need the armor.

Also, I've seen on the wiki that Iceborn Gauntlet used to offer 15% cooldown reduction. Maybe Riot can consider giving it back? Because besides Ionian Boots of Lucidity, we don't have any cooldown reduction items that don't offer either 10% or 20% cooldown reduction. This item wouldn't outclass Frozen Heart because the latter would still have more CDR, armor, and would be better for champions that don't need the Spellblade proc or are using Trinity Force.