The original primary purpose of the Glock was home defense. I already have a 460 S&W which has the same case capacity for powder as a 308. The problem with the 460 is it has a brake on it so you have to wear ear muffs to shoot it and it weighs about 5 pounds without a holster. With holster, earmuffs and ammo you are looking at 6 pounds or so of weight. I used it one year and found the need for earmuffs to be very slow and cumbersome in the dark and when going to pack out an elk it is a lot of weight to carry. I could order a closed muzzle extension to replace the brake but it seems like a lot of trouble.
I am a big fan of the 5.56 with FMJs but the DC regs prohibit owning any rifle or shotgun with a pistol grip or otherwise looking like an assault rifle. So it is not an option for me.
I would certainly not actively hunt black bears with a 9mm and if I was buying a pistol specifically for general carry in black bear country I wold probably go to a 10 mm. Certainly a 9mm is underpowered for a bear by any measure, but it is what I have and it is OK for sleeping in the tent at night and for the one day or so that it takes to pack out an elk.
Here is a video of what it looks like to pack out an elk by your self.
http://www.youtube.com/user/Microcys.../9/7f37MdaTxA0
Whether or not I would actually shoot a bear for eating my elk is questionable being as I do my best to give the meat away anyway and the bear would be saving me from having to pack it out.
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P.S.
One of the interesting pieces of trivia in my life is that Utah prohibits any firearms in your camp while archery hunting UNLESS you have a concealed carry permit. So I actually have a concealed carry permit for Utah just so I can have my guns with me.