There's no good reason that Santa Cruz should specifically stay the way it was 50 years ago or whatever. Personally, I would have liked for Santa Cruz to remain the way it was before people came and tore up all the nature to build a bunch of suburbs, but I can't get what I want either. Culture is inherently ever-changing; Santa Cruz may be _different_ in 50 years if densification and growth was allowed but I don't see how it would be somehow not be Santa Cruz.
There are real, severe economic effects from trying to freeze a city in an arbitrary point in time. At some point the well-being of real actual people needs to be prioritized over the aesthetic preferences and property values of a few NIMBYs. Especially when those aesthetic preferences essentially boil down to hating multi-story apartments and public transit.
Even many of the people who are rabidly pro-transit will be at least mildly against "transit right through my bedroom"; most people don't like being eminently domained.
This usually results in the solution being "motion" of some sort; a city that is run down or out of the limelight begins to modernize and upgrade, and it becomes the new center, and the towns that don't chance ossify and eventually die off.
It may be that the "California problem" is solved because everyone eventually moves away.
