We use way too many plastic bags in the United States (and probably around the world). There are huge patches of trash floating in our oceans, most of which are composed of plastics including bags. They are horrible for the environment. Banning them in favor of paper or reusable bags is the best.
I believe that banning plastic bags would be very beneficial in our society. Plastic bags cause more waste and pollution and are very unnecessary. Using our own bags or bags made from organic materials would be easier as well as help to not cause pollution. Also, plastic bags could be harmful to small animals and children. Getting rid of them would eliminate that threat.
I do not believe they are. If you work out the amount of plastic in a plastic bag, it is insignificant compared to the amount of plastic surrounding the food being carried inside the bag. Why not make people bring their own plastic milk cartons to the supermarket, instead of their own plastic carrier bags. I bet that would reduce the amount of waste 100 fold!
The only person that these bans are beneficial to are paper bag suppliers. I am not a believe in global warming, so the environmental angle does not work on me. The problem that they are trying to combat is pollution, and the easiest way to stop that is more prevalent trash cans.