Help For Non-Mobile Casters

I was thinking how there are multiple items to help out with certain passives. Some of these items were not usable on all champs because of ranged/melee or ad/ap. But what riot did was introduce multiple versions of these items like and for more AOE, and for kiting and chasing, and to help against tanks, and for mana hungry champs, and for wave clear. You get the point. What Im saying is there should be an AP item that gives a version of the **rage passive ** as seen on . Anytime you hit a spell you would get a percentage increased move speed. This would help out so many older caster champions that are immobile. It would be enough to keep them up to pace with where the game is heading without having to rework them due to mobility creep on newer champions. Comment and let me know what you guys think!