In addition to making an entertaining sound, I think they like the smooth texture, and how easily manipulated it is (it's lightweight and moves around when you touch it). I have a cat that likes to chew on/tear off pieces from plastic bags. read more
I know cats who like to play with and get inside them, many like to chew them, and others, like a certain hairball is doing now, sleep on them. Read something once that said they could like and be reacting to a certain chemical in the plastic itself. read more
If your cat likes to play in a plastic bag or a gift bag, there should be no issues-as long as you are present. They deserve to have as much fun as they want to, just use caution and be mindful when it comes to plastic bags. read more