The area would be an even bigger number. Wonder if marketers determined the concept of area was too complicated compared to the concept of a linear diagonal measurement.
Or a 2 digit number is easier to remember and digest than 3 or 4 digits, and 1 digit is too small, such as measuring in squared feet or meters.
TVs are large enough now that square feet would work, for markets where that unit is used anyway. For other markets ... Uhhh, would anyone understand deci square meters?
Of course yes, though more natural would be square decimeter (dm^2) or even square centimeter (cm^2). Though understanding it isn’t the same as being familiar with it.
Or a 2 digit number is easier to remember and digest than 3 or 4 digits, and 1 digit is too small, such as measuring in squared feet or meters.