Years ago, the HRPT was literally a coast-to-coast event. I ran with them a couple of years as they passed through CO and into UT...But at some point, they seemed to "shrink" the route to be more or less a regional cruise. Not sure why.
I like the coast-to-coast format, as no matter where you live, the tour will likely come within a few hundred miles of your location.
Texas is one of two states (the other being CA) I consider to be "ground zero" for the old-car and muscle-car hobbies. I agree that HRM could get more participation in the Tour if they went through the TX/OK area.