Should we buff Echo items?

Currently it seems that AD champion got much better wave clear options than AP Champions – Hydra Items, Hurricane, Shiv

AP Champions got echo items that deal no bonus damage to minions and monsters

If you use Protobelt for waveclear, which is pretty awesome, you wont be able to use it in teamfight cause its cooldown is 40+ seconds while Titanic Hydra have 20 sec cooldown which gives huge advantage.

Echo items deal less damage yet the passive cast rate is nearly twice lower than Shiv which also gives big advantage to AD champions.

Luden Echo deal 100 (+ 10% AP) bonus magic damage why does it have scaling again? 10% AP?

Shiv deals dealing 60 - 160 (based on level), may crit and does increased damage to 99 - 264 (based on level) against minions. An item that can be proced twice as often than Echo, does higher damage and can crit and does bonus damage to minions and monsters

AP champion with 800 AP does 180 magic damage from Echo Shiv does up to 400 magic damage on crit with infinity AP champions invest way more while AD champions can deal up to 400 damage with 2 items. Also does up to 660 damage to minions and monsters

So... Why do we have this item in the game and what is it's purpose?