To be clear, I'm not comparing SDSU relative to Houston, UCF, BYU, or Cincinnati. I don't think that anyone else is doing that either. I'm comparing SDSU to the PAC12 schools which all have very long history of being in major conferences and playing at the highest level.
If you want my opinion on SDSU vs. the B12's recent additions - BYU and Cincinnati are a significant improvement over SDSU. BYU for its history of success and widespread appeal to members of the LDS church, Cincinnati for its recent high levels of success on the field and the fact that prior to the implosion of the Big East football conference it had been in a major conference since 2005, was relegated back to Mid-Major status for 10 years, then will rejoin a major conference in 2023. Both these schools have very strong resumes. UCF and Houston are slight upgrades over SDSU because they've had more success at the highest levels relative to SDSU (both have appeared in and won NY6 bowl games which SDSU has never come close to doing). The B12 and network execs ran the numbers last year and clearly the people who had access to the real data determined that SDSU was not as good as the four additions from last year.
Do you have hard data or evidence on the calculations being used by Fox, ESPN, and the conferences to develop the precise value of SDSU vs the PAC12 teams? I don't, so I can't provide it. The only thing I can say for certain is that you can't just quote the size of the city where the university is located as a selling point, unless you are talking about that school's value to the B1G. Here is why: one of the B1G's key strategies in their 2010 expansion was to increase revenue by forcing local cable/satellite providers to carry its Big 10 Network channel on basic or expanded basic cable. This essentially captured subscription fees from most of the residents of those cities, who had to pay for the BTN because they wanted the History Channel. This was the primary reason for them adding Rutgers - to capture all those TV subscription dollars from the NYC and NJ TV markets. No other conference has a conference TV network with enough fan support to force local providers to carry it on a basic cable package.
Therefore - TV revenue from all other conferences comes from actual viewers of their televised games. TV Networks must have some formula they use to calculate the value of a school's TV revenue, probably based on viewership of games that a school participates in, normalized for the influence of the other team's fanbase. I don't know the formula, but I think it's common sense to say that the size of the city where the university is located doesn't play into it at all. Simply living in San Diego has very little factor into whether or not you watch SDSU football.
By the time I made my post, others had already pointed out that SDSU has low attendance numbers and poor football results compared to the P12 teams under consideration so I didn't feel the need to repeat that. If you want to speculate that SDSU might someday grow into a P5 school, that's fine. But we're not in a position to be taking fliers on mid majors who have had moderate success when P5 schools with proven track records at the highest level are available. If you wanted to argue SDSU vs. Houston last year, that makes sense. Arguing SDSU vs. Colorado is just foolish.