I divide it between "need" and "want". As far as I'm concerned, "need" ends with a fixed 4X for most deer hunting. One of my longer shots, 350 yards, was made with my 3.9 variable set on 3X, FWIW. One shot, DRT.
I like having a 2x7 or a 3x9, just for the greater precision on little critters. And, generally, higher magnification helps in target shooting.
I also like using the higher magnification when hunting from a stand, as a final check as to whether or not the buck is really good enough to shoot. But I don't regard this latter as a necessity; I have binoculars.