Which way is up?
It could make sense, but doesn't
"Up the neck" always refers to moving to positions of higher pitch, not physical location. I suppose you could say that it makes sense because the instrument could always be turned on its side or upside down, and this way the direction is still the same, up in pitch.
Well, then what about the body. "Up" is always in just the opposite direction, toward the neck, not toward the bridge. I guess you can justify that direction because it means "up toward the neck" as it would in the human body.
I dunno, maybe we should just accept things the way they are sometimes without trying to overanalyze 'em.