The lever action carbines are probably nicer to carry than any other rifle I can think of, and that has more to do with their popularity than the cartridge they are chambered for. The more difficult the country, the greater the distance one travels on foot, the more important it is to have a compact light rifle. Any gun in a dangerous bear encounter is better than no gun, and a rifle that doesn't fatigue you after hours on the trail will be quicker to get into action than a 10 pound bolt gun with a 26" barrel.
Having said that, there is a difference between a hunting rifle and a protection rifle. Just because you can kill an unsuspecting bear with a .30/30 doesn't make it an appropriate cartridge for protection against what is arguably North America's most dangerous game. The old boys who elect to carry a .30/30 in the Alaskan back country, probably have a lifetime of bear experience that keeps them out of trouble. The once a year hunter might not. I seriously doubt that those Alaskan's would choose to pack their thutty-thutty's when they are crawling along the grass tunnels on Kodiak or Admiralty.
If we think about what happens when a big game animal is shot, surely it must give us pause to consider what might happen in a dangerous bear encounter. When you shoot a deer, how often do you get a bang flop? I'm, not talking about a one shot kill here, but where the deer drops like you pulled the rug out form under it. Not that often I'll bet. A bear, particularly a large species of bear, has bigger bones and denser muscle for the bullet to overcome. In a defensive shooting scenario, the bear will not be broadside, he will not be quartering, he will be head on. If you shoot a bear that's 20' away, and he is not killed, disabled, or turned immediately, you best be prepared to get whupped! The idea that you should intentionally seek out this confrontation with a mouse gun is laughable. The surest way of stopping this guy is to break a big bone. You don't have time to get fancy with a precision shot. If you haven't solved the problem in 2 seconds, you will not solve it. Lets consider the head shot for a moment. A big bear's head is huge and massive. That certainly doesn't make it bullet proof, but it does make bullet placement difficult. The brain is only as wide as the snout, and the bullet must strike behind the eyes and ahead of the ears. That's tricky shooting on a moving animal, and a bear's head is often in motion, different than his forward progression. You've got one chance to save your life, if you wait for a head shot, your chances are diminished, and things are already going wrong.
Those of us here who make part of our income from bear security prefer to carry powerful rifles, but the choice of rifle must be within the experience and limitation of the shooter. I have every confidence that my wife can protect herself with her .30/06, and I won't even allow her to shoot my .375. We were shooting one day last summer and from 5 yards she repeatedly snap shot 5 rounds into an inch, the longest time from signal to shot was about 2 seconds, the fastest was very fast, but I would guess about a second. I load her ammo, I make sure every round she carries will function in her rifle, and I choose a tough bullet, in her case a 180 gr TSX. I would have preferred the 240 gr Woodleighs, but those long torpedoes won't stabilize in her 1:12 barrel. I am confident that the 180 gr TSX at 2550 from her 21" barrel will survive a frontal shot on the biggest bear, and typically the trouble makers are adolescents.
To hunt in bear country and disregard the possibility of a dangerous bear encounter is unwise. To not be alert for bear sign or evidence of bear activity is unwise. To carry a mouse gun when you have other options is likewise - unwise.