There was a pretty good discussion on a reloading site about this. I don't think they are needed for anything myself. What is important then tho is choosing a proper cartridge and the best bullet for what your hunting. A 270 with a 130gr cup and core bullet is to me a bit light for anything bigger than a deer but with a 150gr bullet the picture changes a lot. 30-06 and a 150gr bullet is in the same league but up the bullet to 180gr and everything changes.
So what do you think? Do we really need them?