A hard tip is theoretically beneficial for penetration, but the number of real world scenarios where insufficient penetration is a problem is few to none when simply using a conventional domed pellet. And in most cases a quality domed pellet will be more accurate, which is of far greater benefit to producing a clean kill than a pellet that penetrates deeply but misses the brain or vitals.
Where the goal is maximizing knockdown power, the opposite end of the spectrum is usually preferable. A pellet which expands (hollow point) or simply a flat nose (wadcutter) produces more tissue damage than a dome. Provided it arrives with enough velocity to penetrate, that is. For most everything except a shallow angle frontal shot on medium critters (e.g. raccoon) or a thick-skulled animal like a mature hog, that's not a problem. But there's usually a tradeoff in accuracy so the nod may still go to a dome if the distances stretch out.
