Simple - there are no panels in existence.Just checking, I would have thought the larger 17" models would be a better fit for the higher resolution screens
Why are those options not available?
An update several months later - 17" 4K panels are now on the radar:
http://www.panelook.com/B173ZAN01.0_AUO_17.3_LCM_overview_25358.html
Unlike the rubbishy 48Hz Pentile 15" Samsung screens, this is a proper RGB 4K 17" screen.
Expect it to take several more months before laptops pop up for sale with that screen in them...