I largely agree with the sentiment, Robb, but there is a bit of truth to what both Mariani and Quintana say. There is a degree to which people trying to offer their home foods from Mexico can be stymied by local tastes for fajitas, nachos, and cheese enchiladas. And I would be willing to make the case that most regions of Mexico have more complex cuisines than Texas. If I remember correctly, Pilcher does touch on this a bit in that much of the Tex-Mex tradition in a restaurant, not home-cooking tradition.
That said, Mariani is a moron. The east has nothing on the west when it comes to Mexican food. Two words for Mariani: L. A.