Because Texas isn't "cool" anymore. All of the other programs in that state, save for probably Tech, have some combination of more recent success, innovative offenses, dynamic coaches, or are media-darlings.
Texas, meanwhile, hasn't accomplished squat this decade. Plus, their offense has been gridiron ambien, and I don't know many people that would classify Charlie as "dynamic." Most kids being recruited now were 10 or 11 years old the last time Texas had any national relevance, and were around 5-6 when they won a Natty with Vince. Texas fell into one of those perfect storms during their 2003-09 run. They were the big dog in the state, as Baylor/Tech/Aggy were all down. TCU was stuck in a mid-major conference, and Houston was an after-thought. Then, Mack got fat and lazy, stopped recruiting QBs, and everybody passed him by. It's gonna be tough to climb outta that hole, and I don't think Charlie will ever get the traction to do it. If/when they move on from Charlie, that hire will be CRITICAL. They need a dynamic program builder to come in and totally revamp them. That guy might be [[over in Houston]] Tim Beck.