On the one hand, you know airlines as a group have had the bag charge idea on the books for years, just waiting for a reason to implement it. American is leading them all, but if they pull it off, all major hub airlines might eventually follow.
On the other, they really are experiencing huge cost increases due to fuel costs, and have to make the money up somewhere. This model allows them to avoid raising actual ticket prices, though with 2 bags round trip being 80 bucks, this might be argued to be deceptive in terms of overall cost to the traveler.
The airlines have always had a bag fee. Before it just was figured into the total price of a ticket.