Gaget,
This is one of the problems of the digital age, the old methods of display or calculations don't fit neatly into it.
I remember when tallying up work hours and minutes when servicing aircraft, the only way to do it was by the long hand method, for even a small service it could take all day, and many sheets of paper.
Building an extra display into my Sino units just to calculate angles between minutes and seconds to digital would make it even more complicated and costly, so I reckon that is why they just do the digital bit.
Bogs