I can't disagree with you or what DGib wrote. If SDSU doesn't provide value, then they just don't cut it. As insane as it seems to not have a SoCal presence, it's also insane to cut SDSU a full share when it doesn't warrant it.
I struggle a bit knowing that there is a chicken-and-egg thing going on here, though. I am confident Houston would have provided enough value over time once it started playing in games that mattered. SMU, and even more so SDSU, are uncertain. Why would casual fans, or even many alumni, in D/FW watch SMU play South Florida when they can watch UT, A&M, or even TCU playing games that matter? Not to mention the Cowboys. I live in Texas and I haven't been going out of my way to watch SMU playing AAC games, but I usually will watch most other local teams if they're on, in part because there are alumni around here from all those other schools, and in part because I will have just about any football on that I can.
But people in the D/FW area and in Texas generally will watch football that matters, and I know a lot of them would watch SMU playing Big 12 teams. Would they consider playing Pac-12 teams big-time enough to tune in? Generally, it seems reasonable to think they should be, since the Pac-12 is P5 and most of its teams are just as good, but it's not clear-cut. For years, due to Hansen, Scott, and half-assed approaches by Pac-12 schools, people around here view the Pac-12 as inferior, and there is no history other than with CU. Texas fans don't care about most Pac-12 schools, much like how Seattle casual fans don't care about Texas Tech or Baylor, but even more so due to the inferiority, actual and perceived, of football on the west coast.
In SDSU's case, with the Chargers out of the mix, that's somewhat interesting in theory. There should be some room to draw casual fans if SDSU is playing in games that matter, and I think most west coast people would find Pac-12 schools a lot more compelling than people in Texas. I grant that you can't get around the casual nature of most of these west coast cities, though. People around there simply may not give enough of a damn.