We’ve written about the slow demise of booking bonuses before, and the last of the “big six” airlines has decided that members no longer need an incentive to book online. As of last month, American AAdvantage members can no longer earn the 250-mile bonus for coach or the 500-mile bonus for first or business class tickets when booking online. Bonus miles for online booking are still offered by low-cost carriers such as Southwest, JetBlue, AirTran and Frontier.