i think that's because of the domestic demand for the lenses in Japan is overwhelmingly strong.
I just returned from Tokyo, at Bic Camera, Yodobashi, Softbank and other big electronic stores all stock panasonic G and L series camera and accessories very well (and in all colors). Bic and Yodobashi were taking pre-orders, other smaller camera shops were doing the same. won't be cheap though, think it was in the region of 100k YEN.