I wonder whether a wireless remote makes sense for different and creative usage of the camera, where you are standing away from it. I can't think exactly what creative uses, though . I am thinking out loud.
Another advantage of the wireless remotes is that they are smaller, it seems to me, on average, than wired ones.
Still, from the specs of RC-1 and RC-5 by Canon, I can't understand if you can lock the shutter open, or even just keep it open by keeping the button pressed.