Mandatory seismic retrofit codes and regulations are increasingly being enforced in cities across California. San Francisco has implemented the Mandatory Retrofit Ordinance, and a similar (and even more expansive) requirement is expected to go into effect in Los Angeles later this year. The aim of these regulations is to create a more seismcially resilient building stock, limit costly damage, and most importantly - protect life safety of building occupants in case of a severe seismic event.
There is possibly another argument for compliance: liability. Ignoring a requirement to make structural improvements could render a property owner/operator liable for damages (and could certainly void insurance coverage) in case of an earthquake. In a very unique legal case, a property owner in San Francisco was charged with negligence for not implementing mandatory seismic strengthening, and was held personally liable for the deaths of two tenants who were killed when the property collapsed.