I'm with the "because it's fun and cool and amazing" crowd - reason enough if you want to. But I'm less sure that anything done with a pinhole can be done with a lens. A pinhole is intrinsically soft focus, varying from quite soft to almost sharp. That alone can be hard enough to do with a lens but the other facet is that the pinhole creates an image with the same degree of sharpness, or unsharpness if you prefer, at all distances. You can stop down a lens, but that just makes it sharper until you reach diffraction problems when it starts getting less sharp again. I know of no way with a lens to render the image uniformly soft focus from inches to infinity. That gives a pinhole image its own aesthetic.
I'm thinking of trying it with some of the infrared film in my freezer.