As was mentioned in the broken off bear thread... you can't follow a blanket statement like this... you have to consider your surroundings.
One specific exception is in GSMNP:
1. First of all, there is the legal requirement that you hang your food on the bear cables.
2. One of the special differences in GSMNP compared to most of the rest of the AT is that you can not just camp anywhere. You basically have a large number of people camping in a relatively few spots. This concentration of people means that mice (and bears... but lets not go there again) know where all the camp sites are located. So when you keep food in your tent, you are encouraging problems between people and wild life.
3. Come on... the bear cables are there and simple to use. Utilizing them cuts down on the people that will camp in your exact spot in the future from having issues with wild life.