At the beginning they weren't "kinda crappy" because there really wasn't anything else you could compare them to. Nobody else made a camera that you could strap to your chest, or your helmet, or your motorcycle while you did something action-ey. They had fully waterproof cases too, so you could take them underwater.

As a camera, they weren't amazing. But, people weren't using them to take wedding pictures. They were using them in situations where a normal camera would be too heavy, or wouldn't stay attached, or wouldn't survive.

There's a reason they became a household name. They enabled people to do things that had never been done before, and they changed the way a lot of sports are shot.