I am not a biologist. I know this because I've taken biology classes in middle school, high school and college. When I read this excellent post from PZ, I suddenly realize the point of exposing everybody to a broad range of sciences in the primary, secondary and post-secondary education.
The point isn't to create an army of experts in genetics, physics, geology, or any of the other sciences; the point is to inform the general population enough about the complexities of the sciences that they are able to recognize the expertise of those who do devote their lives to scientific study.
It's about teaching people what they don't know.
Basically, it's how we as a society are supposed to fight a widespread Dunning-Kruger effect in STEM fields.
Maybe what's needed in STEM, in addition to the current pedagogy, is to acknowledge the difficulty of the field, and point out that while not everybody is suited to every subject, it's important to know that people are capable of becoming experts, and that some baseline is required to recognize when one's own knowledge isn't enough.
I've always found the idea that the purpose of the educational system is to churn out ready-made cogs in for the economic machine instinctively offensive. I'm not really the best advocate for liberal arts, but I had always appreciated their value, but now I think I actually get it. We all need to know some stuff, at least enough to have an idea of what we don't know.
And here's where I think our educational system is failing.