There is something horribly wrong with an education system which leds people to think this, its the equivalent of 50% of americans coming out of maths thinking 2+2=5.
Not really. Failing to understand evolution is far less likely to inconvenience you personally or professionally. From a purely utilitarian perspective understanding evolution is of little significance outside of a few professions.
But the point is, it's a scientific fact and the fact that a majority of Americans don't believe it is troubling.