Why do you assume all designers are even working on HTML/CSS apps? When you get down to mobile, do you expect them to be able to code in C++/ObjectiveC/Java?
A good designer will understand the limitations of the platform they are designing for. My wife designs for S40 feature phones with plenty of limitations. There is plenty of back and forth between development and design to ensure that the design works with the limitations of the software and hardware (though devs often push back too soon).
A good designer will understand the limitations of the platform they are designing for. My wife designs for S40 feature phones with plenty of limitations. There is plenty of back and forth between development and design to ensure that the design works with the limitations of the software and hardware (though devs often push back too soon).