I'm not sure, its something I have been seeing with alot of the jam games here. From my experience and my own personal preference, i feel like if a bullet touches my character i should take damage. In that way it almost feels wrong to have a whole character and only take damage on the center pixel. But I'm not sure if everyone would agree with me. You also figure out pretty quickly that that is the weak spot so I don't think clarity on that was my issue.