Travel Agent anyone?
There are a few reasons. One, if Amex books your tickets, regardless of the color of your card, they are happy to provide you with help if you need to change your flights. Flights canceled at the airport, being somewhere that you need to go at the last minute and they have access to all the airlines which is a huge bonus. I have also found it helpful for figuring out how to use the accumulated miles which you never seem to be able to use when you want to. BTW, I do check the flights and prices before calling/emailing AMEX because I want to be informed but I pull the trigger through AMEX.
One caveat is not everyone on the other end of the phone is knowledgeable. I have been using the same guy for years. He is the best. I just shoot him and email and he is on top of it, always. I have sent people his way. Today he did something that was beyond the call of duty which is why I had to write this post.
His name is Wayne Bolton and if you have an AMEX card, and want to use the travel department, ask for Wayne. He is fantastic, knowledgeable, knows the system, crosses his t's and dots his i's. Best part, he is free.