The change is an effort to make things less confusing for travelers.
As of today, American Airlines has undergone a major reservation policy change: passengers can no longer reserve seats on AA flights for 24 hours without putting money down. Instead, American Airlines is implementing the more common policy that allows passengers to cancel a purchased ticket within 24 hours of booking for a full refund. The Washington Post reported that AA explained the change comes in an effort to reduce confusion for travelers, ultimately aligning their travel policy with what has become the norm among major carriers.
The 24-hour hold policy will not disappear entirely, though: travelers booking tickets with reward miles still will be able to hold a ticket for a day before making the final purchase.
While both policies have their benefits, the hope is that the new one will be less confusing for customers, while still offering a reasonable amount of flexibility.