One of the ideas behind such openings that give away pieces is that the material advantage isn't of any use if the material is undeveloped or poorly developed. So, white has a strong attack when black is at his weakest. Usually, these gambits can be neutralized by black returning some of the material to gain time. But they are fun to play and, since the lines are drawn right off the bat - white wants a quick kill while black wants a static advantage - there's little else to think about than finding the moves that support those ideas.