Go look at Martha Casanave's work at www.marthacasanave.com. She did a whole series of images alone the Monterey coast using her pinhole camera. They're quite wonderful. She and Ryuijie Douglas were here in Portland, Oregon for a workshop and the attendees just ate up her work and want her to come back for a pinhole/cyanotype workshop.
To say "Why Pinhole?" is like saying why use Holgas? Why Platinum? Why color? It's a preference. Photography is not one way or another. It fun to experiment. To explore. We currently have the sharpest lens and the ability for the cleanest tonal images but sometimes its fun to outside the box and try something simple like pinhole and sometimes doing this opens another way of seeing an image or a whole series of images.