The way to think about security is as a system of layers, each of which filters out ever more sophisticated attackers.
We should care about all kinds of attackers, and not assume that the protections against the most sophisticated will obviate the protections against the least sophisticated.
The Swiss cheese model is what people use to sell you more 'security' related software systems that inherently involve more problems. (Also cheese is not very durable, even the kind without holes.)
