Computer monitor sizes are measured diagonally due to historical conventions established in the 1940s, initially linked to the 3:4 aspect ratio of 35mm film. This method simplifies the representation of screen dimensions, allowing for easy calculations of width and height from the diagonal measurement. However, with the advent of HDTV and the 16:9 aspect ratio, this convention has become less effective, as it does not provide integer dimensions for all aspect ratios and can lead to confusion regarding actual screen size. The diagonal measurement does not accurately reflect the usable screen area, particularly when comparing different aspect ratios. Users express a preference for knowing the height dimension to better understand the screen's actual size and usability. Additionally, modern monitors offer features like rotation for enhanced viewing options, which can improve the overall experience compared to traditional CRT TVs.