I doubt IC: piercing will work with eldritch blasts. If anything, it works like magic damage; like blade barrier has slashing damage and meteor swarm has bludgeoning damage. Both of those spells are made stronger via force/impulse spellpower. Penetrating blast will be no different.
I liked the untyped damage better, but at least this gives another damage option to warlocks. In all honesty, no warlock in their right mind would use any other eldritch essence other than penetrating blast if it was still untyped damage. That's probably one reason why they changed it: it completely overshadowed every other essence.