I've been to many National Parks. I'm very fortunate that a few good men like John Muir and Teddy Roosevelt thought it was important enough to have national parks. They were two of the many heroes that have been there throughout our nation's history to stand up for preservation over the continued exploitation of our natural resources. They thought that some things were worth saving. The main question is, why?
The truth is, some places are worth preserving simply because they're there. They shouldn't be preserved because they have some valuable natural resource that we might need later on, as Gifford Pinchot viewed the forests in the Sierra Nevada, or even because we want the citizens of our country to be able to enjoy these spaces, or because we want to preserve them for posterity. Our national parks are beautiful places. Yosemite offers stunning unique granite formations, while much of Yellowstone is itself and active volcano. Many national parks in Alaska contain vast tracts of wilderness, where the complex ecology is protected from future development. We need to protect these places, because they preserve the beauty of nature.