The refusal to accept evolution has significant consequences for public policy. First of all, it validates choices-of-faith over choices-of-fact, which opens the door for wilful ignorance on other science-driven topics ranging from effectiveness of condoms in fighting STDs to global warming. (Admittedly the causality may be slightly reversed here, but the logic remains the same even if denial of sexual research precedes evolution denial.)
Once those kinds of choices come to seem right, with all the attendant warm feeling of righteousness that accompanies a sense of doing God's work (yes, I was raised for a time in a church and I'm familiar with this -- that's not snark), they become entrenched in our nation's electoral politics.
Once they become entrenched in our nation's electoral politics, we have problems ranging from local school boards adopting ID to an entire national energy policy which actively denies the presence, effects or risks of global warming.
We are deliberately electing a generation of leaders and educating a generation of children whose decision making faculties have been consciously crippled by the blinders of faith. That didn't matter much in the Middle Ages, when the effects of human agency on the world were largely limited to local pollution and long-term deforestation, but it matters immensely in a world of industrial emissions and nuclear policy.
You get to choose your faith, but you don't get to choose your facts.