WA Prime for DX question

[fmw]

Can any of you smart lens-heads explain why the 24mm (and 20, and 28) 1.8G lenses are so long? The 85mm and 50mm are nice and stubby, easier to carry around...

Lenses are made wider by adding extra elements/groups to the front ('retrofocus').

A necessity for preventing the back of the lens from being struck by a swinging mirror. The reason the Leica range finder wide angles are so amazing is their ability to sit close to the film/sensor plane.