Not defending it but...
Eating an enemy with tahm w was normally more detrimental than good, especially in 1v1 scenarios, tahm kench actually losses dps if he eats his target so its mostly an outplay sort of thing, like against jax counter attack or tryndamere ult
Basically would you rather keep autoing your target and not eat them so your next q will stun again, meaning you could keep auto attacking with max stacks and keep dealing full damage, or would you prefer to eat your target which removes your stacks from them and does less damage than your q (ever since the % max health nerfs which pretty much gutted his w damage)
The only time I really use it for damage is when I need to execute a low health enemy right before I die since it does more damage than an auto attack and my q is already on cooldown.