[dredmorbius]

For all its coastline, there's relatively little of it that's of any strategic significance at all.

San Diego, Los Angeles - Long Beach. Malibu. Ventura. Santa Barbara. Pismo Beach. Big Sur. Carmel. Monterey. Castroville. Santa Cruz. Pacifica. San Francisco. Eureka-Arcata.

And that's along some 800 miles of coastline. Only the starred cities are of any particular size now, and most would have been far smaller during WWII. The Japanese may have chosen to avoid cities as they were more likely to be effectively defended.

Santa Barbara's oilfields would have been a modestly significant strategic target, though US oil facilities elsewhere, particularly in Texas, were vastly larger. California also had major inland fields near Bakersfield, Taft, and throughout the Los Angeles basin.