So what was the goal with introducing Luden's Echo?
From my perspective, the item was introduced to help mages with low mobility/waveclear.
However, the champions I see buying the item already got high mobility and waveclear, and it only further increase their advantage.
and 
both fits in those category, and I really don't think they need that extra MS/AoE in their kit to work properly, especially Kat.
To make it worse, the item does not give any mana regen, so only mages who have low mana cost or no mana at all (again Ahri and Kat) will rush it.
So far, I think it only "helped" the mages who did not "need" it.
