It'd be fine if it were actually consistent and they picked different locations. But 'High Sierra' is a region, 'Yosemite' is a park in that region and 'El Capitan' is a large rock in that park (side note...a large rock that was climbed without ropes this weekend...Alex Honnold is both insane and a huge inspiration). They've essentially made the last three releases about the same place. It's lazy and inconsistent. And it's not like there's a shortage of exquisite places in California. Big Sur, Shasta, Lassen, Mendocino, Lost Coast, San Simeon, Joshua Tree, Catalina, Monterrey Bay...just off the top of my head, I've named 9 better California places that they could have used for their releases.
It'd also be kinda funny for them to jab at Microsoft's advertising and have an OS X Mojave, since it would fit with their naming scheme.