Yes, it’s a more flexible credit type. If you cancel a ticket, you often still receive a Flight Credit… sometimes a Trip Credit (which AA has been increasingly working towards). Even if you get a Flight Credit, people have had success getting AA to convert them into Trip Credits, or have employed the workaround of using the Flight Credit for a very cheap ticket, which causes the residual to be issued as a Trip Credit. So you still have options, but definitely easier to just refare.