This! I see this as a CA issue, not a BOA issue. As underfunded as the performing arts are in most places, it's worse in CA. Not only that, but the cost of living is very high (at least in the heavily populated areas that would have the most potential to have competitive marching bands). High cost of living directly affects how much individual families can devote to things like band. High cost of living and lack of support, also, drives away many great educators. I am a CA native and am sad to see what has happened to my former state.
Interestingly, though, in regards to BOA in CA, I believe the "CA" regional was originally called the Western Regional and hopped around various western states, then as interest grew, more regionals were added and eventually CA had a CA specific regional (and then 2). As recently as 2014 there was only 1 BOA regional in CA. I don't find it strange that there is only 1 this year and (while this is just conjecture), I imagine Bakersfield was chosen either due to cost, availability or because it is central between the previous CA regional locations. That said, no one wants to go to Bakersfield and it would be hard to justify the BOA entree fees and cost of travel for many programs (hence the low registration)....there are CA bands going to the AZ regional, the UT regional, the San Antonio, TX super regional, and Grand Nationals.