While I agree with Ricky to a certain extent in that you don't have to shoot everything, I similarly find the excuse that handguns are too much weight to carry to be similarly hokey (save for those who have actual physical maladies that preclude things like carrying extra pocket changes and the like).
However, I see no reason not to carry a pistol.
It was noted that pistols may not be much use against bears especially given the lack of range, power, and accuracy at distance of pistols compared to rifles. However, I have been surprised by the number of bear attack stories where hunters managed to lose their rifles in the attacks and those where were attacked that managed to produce knives, pepper spray, or pistols while the bears were chomping on them. Having a "get off me" weapon does seem like a good idea.
A rifle sighted for 100 yards or more will be difficult to shoot accurately or quickly at close range especially if its shouldered. Also shooting straight down at hogs or coyote etc. from a stand would be difficult.
I don't know about quickly, but at close range, it should not be a problem. Given parameters of sight height, velocity, weight etc., basically POA/POI differences out to 100 yards for most centerfire calibers should not have a difference more than 0-3"
Say you have a .223 rifle firing a 55 grain spitzer hunting round at 3000 fps with a sight radius 1/2" over the bore radius and sighted in at 100 yards. The POA/POI difference ranges from the greatest value of 1/2" low at contact to 1/3" high at 60 yards.
How about with a scope 2" over the bore? Then you are 2" low at contact and the difference reduces to zero as you approach 100 yards, so never more than the difference between the sight radius height over the bore radius.
How about a big ole heavy .45-70 325 grain Leverevolution round? Out of my Marlin, I get about 1860 fps and have a sight over bore radius of about 1.5". At contact, the round would be 1.5" low and it will climb to a grand height of 3/4" over line of sight at 60-70 yards.
So unless you are trying to shoot off a particular toe on a creature, being sighted in at 100 yards for a hunting rifle should not produce such a difference in accuracy that you could not make a good shot.