PK makes HC, with out it every one would be 99 and it just adds to the challenge.
Only hack that I think is destroying in HC is drop hacking ie: the old Druid drop hack, because there was no way to avoid it, all others there are ways to avoid.
Blizzard: "Don't use map hack"
Me: Hmmm you patch the potions drop hack and then i'll stop using the map hack that prevents you from dropping.