Most kit that needs to be charged via USB, is going to have to use a standard USB connector, unless you want to do some fairly serious modding. After all half the point is that the USB connector is broadly fairly standard (even if I do have devices which use USB, Mini-USB and Micro-USB for power).
For in-line connections away from the device being powered, and assuming that equipment is put somewhere waterproof (assuming it isn't waterproof anyway, like my Garmin), then I can see the usefulness of a fairly heavy duty, waterproof two pin DC connector.