Originally posted by Rondec Sony has tended to under engineer their lenses and then rely on in camera post processing to take care of vignetting and distortion, but even they decided that they needed a line up of bigger lenses that are (I think) sharp without a whole lot of post processing. The G Master lenses are quite large, but there is a group of photographers who want that sort of lens.
The G Master lenses, despite their size, were designed to be as small as possible while still meeting their specific goals. So in terms of lens performance, size does matter.
Part of the reason for the growing size of lenses is the development of high resolution sensors. The G Master lenses are designed not merely for the current stable of high resolution sensors, but for possible future greater resolution sensors as well. It's likely similar thinking is behind these new DFA* lenses. It's the inevitable result of megapixel madness.
I have no issues at all with Pentax making these mammoth f1.4 primes. I'm confident they'll be the finest K-Mount lenses ever made, combining the resolution of the Sigma monster "Art" lenses with the rendering and colors Pentax is known for. The fact that Pentax is not making the sort of DFA lenses I might want also doesn't bother me one bit, as it prevents me from being tempted by the lure of FF, thus saving me thousands of dollars.