Should we invest in more "alternatives" to bridges and highways? I like mass transit, but the loss of the bridge points to a lack of redundancy, not to inadequate mass transit. Suppose BART had been shut down. (An accident in the tube? A strike?) Would the question have read, "Should California invest more in alternatives to mass transit such as additional bridges and highways?" Was a bias showing in the way the question was worded?
The next question might be: how much would such an investment cost, and would the expense exceed the value (i.e. having a bridge down for a week). That is a good economics questions, without an obvious answer. In New York City, there is always pressure to buy more snow removal equipment, but it turns out to make more sense to shut down the city for a few days when the rare snowstorm hits. So it may make more sense to live with a fallible system, and to spend our money elsewhere.
There are no trivial answers to these questions. If we want the decision to be based on economics, then a detailed analysis must be done. If we want to encourage mass transit, then we should not use a closure of the Bay Bride to support a position that is really based on totally different considerations.