Protestants appear to honor Saint Paul more than they do Saint Peter, so why do they neglect ......?

I'm not sure that most Protestants would agree with this interpretation. I don't know of a single Protestant who has ever denied the crucifixion or the crucifix -- they just don't see it as the 'final word' on the subject. Also, this goes more to the medieval reformation battle over icons, statues, images and such more than it does to Pauline theology. Many Protestants during the Reformations were reacting against a perceived idolatry, and thus worked to eliminate most if not all possibilities in that direction. The traditional crucifix as an image (as distinct from the theological idea) was one of those.