To be fair, thats a bit more than QoL buff. On the other side, if he managed to hit someone mid-dash with his E, he is already rewarded with longer stun(rather than waiting for their dash to end and stun in melee range).
Im not really sure he needs this kind of buff, and it will feel a bit off for experienced Xerath players for a while, if they are used to throwing EWQ(W at himself) at enemies dashing at them. Ahri had it better because her Q is linear and her W auto-aims at charmed target
Now if there was an option added to stop charging Q and get the mana back without waiting full duration, that would be a QoL buff.