The issue is that CLT is not positioned to be any kind of big international hub. PHL is the basket where all the eggs are going. Just look at the exPHL routes that have been "upgraded" to a 787 and new routes that have been added there. CLT has been getting overflow routes to large Europe cities to supplement PHL during the busy travel months, but not much more.
.
Disagree. Not only is Charlotte positioned as an international hub, its currently used as an AA international hub for the Caribbean. I suspect CLT sees more Caribbean pax than PHL sees in Trans-Atlantic. TA is more glamorous and gets nicer, newer planes while CLT is stuck with LUS A321.