seems it could be misleading though and could encourage makers to make wide screens that aren't very high rather than sqaure ones. Here's my thinking:
A square screen 20 inches by 20 inches has an area of 400 sq inches and a diagonal (pause while I recall my pythagoras) of 28.3 inches.
But a long thin screen with the same area that measures 40 x 10 inches would have a diagonal of 41.2 inches.
So the long thin one has a much longer diagonal but is it really any bigger?
Okay a square screen would look odd, but maybe the screen area is a better guide than the diagonal?