I'm not sure what all the fuss is about, Panasonic/Leica make a 12-60mm (24-120mm in 35mm) that is f2.8/4.0, and people are getting excited about a f4,0 only lens.
Even up scaling from MFT to APS-C this still looks a sizable lens. Why not make something that is better than the opposition, say a constant f3.5.
Come on Fuji make a statement.