Would you pay extra to board your flight sooner and "gain more time to store carry-on luggage"? That's what American Airlines has begun selling, for an additional fee. The airline has announced a new "program" called "Boarding and Flexibility Package" that allows passengers to board flights earlier (in "Group 1", just after first, business, and elite frequent flyers). The package also allows you to standby for an earlier flight without paying AA's new $50 same day change fee, and it allows you to change your itinerary for $75 rather than the normal $150 fee. So if there's a good chance you may have to change your ticket, it may be worth considering this option.
And with overhead bins frequently over-stuffed, we imagine that some passengers will say "yes please!"
This new option will not be offered in all markets or on all routes, and the cost varies depending on the length of the flight.
Southwest Airlines also offers an option to board flights early for $10 each way. So perhaps American has been following Southwest's success in selling this perk.