Cinematography Database's Matt Workman discusses the history of the 16:9 aspect ratio and also gives some compelling reasons as to why it isn't necessarily the most appealing aesthetic.
He writes, "We were never meant to shoot motion pictures in 16:9. Yet modern cinematographers are forced to work within it’s disproportioned prison walls every day and most don’t question it’s origin. I personally find 16:9 to be an ugly aspect ratio, but it is the current standard for HD (1920×1080) and UHD (3840×2160), so we will be viewing 16:9 screens for a very long time. In this article I want to discuss the history of the 16:9 aspect ratio to educate modern cinematographers so that we might influence the next 'standard' aspect ratio."