Jonny Scaramanga wrote a good post explaining why creationism matters.
We should be worrying about creationism. But everyone is worried about it for the wrong reasons. Yes, creationism is false, and young-Earth creationism is particularly ridiculous. But with thousands of false beliefs in circulation, why should we particularly care about creationism? It doesn’t make much difference to my daily life whether or not I accept that all life on Earth shares a single common ancestor, or that the planet is 4.54 billion years old. Even in science, there are limited areas where the fact of common descent is immediately relevant.
The trouble is that the areas of fundamentalism which are truly oppressive— the denial of women’s rights and bigotry against LGBTQ people, for example—are intimately bound up with creationism. You’ll notice that, amid its busy schedule of producing pseudoscience, Answers in Genesis has found time to oppose gay marriage. There aren’t a lot of copies of The Selfish Gene in Quiverfull homes, either. These facts are not coincidences.