The chunkier part I understand, as for the cost, they could make them an upsale or something. I wouldn't mind a wireless edition either, there is already the Sennheiser MM 100, so it should be possible.
I have heard quite a few much more expensive headphones than the PX100-2, but I end up preferring the immersive sound of the PX100-2. Are there any other headphones with similar sound profile?
To my ears, the Koss Porta Pro has a very similar sound.