While getting a sleeping bag for short camping trips, why not get one for long trips or for survival scenarios?

As long as it stays dry, it will work great and be lightweight. But over long treks or a scenario where you are camping for a whole winter season, your sleeping bag will absorb more and more moisture making it less able to keep you warm. Condensation is a major problem in winter tents; your breath condenses on the side of the walls, and, over time will begin dripping down. If it came to a long winter excursion, a down sleeping bag's effectiveness will sadly fade when you need it most.

I'm kind of a prepper, so I consider such things. But youdowhachyouwant.