Is much of the "old" equipment in need of major maintenance? Maybe so, but that argues for establishing a high-volume maintenance depot in Kuwait instead of going the far more costly route of shipping the stuff out of theater and bringing in new equipment. Rotating equipment struck me as rather inefficient too. However, I think you are right about the need for major maintenance. Perhaps it's just too costly to establish a major maintenance facility in Kuwait. There is a lot of heavy, specialized equipment involved in depot level maintenance, and most of the people who do it are civilians.
Maybe someone who has some knowledge on this subject will weigh in and shed some light on this.