- AA didn't serve ATL at all until the early 1980s... probably the largest market that they did not serve for so long.
- DL and another airline (EA, later J7/FL) are well established at ATL.
- TW and to a lesser extent NW tried to establish a modest operation at ATL and failed.
- After EA went under, AA considered closing both the BNA and RDU hubs in favor of a consolidated ATL hub using EA's gates, but AA decided against it.
- FL has grown so much that they have price power on many ATL routes.
Add these factors up and AA probably doesn't have the appetite for any more ATL service than they have now.