Easier to obtain and retain tracking fields. Tracking and stadium conditions will be better known by the competitiors. Possibly better rates for both the stadium and hotel with repeat business. More centrally located area. Loss of an annual event by the membership.
Annual events are a crucial part of USA and help bond the membership together.
Having the event in a central location will in effect exclude those members who could attend the event if held within their region but are unable to travel every year to the event. It is an unproven assumption that this would produce a higher standard of event. The regions have consistantly hosted high standard events. This is an event used to choose the National team for the world championship known and standardized conditions do not contribute to the choice of the most competative team. Hotel and stadium costs vary for various locals it is probable that lower rates and equal or better standards can be obtained by the regions.