Being able to see more text (webpages, news articles), and longer lists (email inbox, code) is more important to more people than having a laptop that can watch movies. Split-screening on a laptop is rough no matter the dimensions. In the best case scenario you have a wide laptop and you see two panes, but a miniscule amount of rows on each pane.
Squarish laptops have been a breath of fresh air for me.
For me 16:9/10 is way more "useful" than 3:2/4:3 ever was (had that for ages, wouldn't go back). I love being able to have two different things side-by-side, e.g. an editor and a terminal, on a 13" screen, at a font size I can still read well. I definitely wouldn't buy a square-ish laptop screen.
16:9 is great if I wanna watch movies all day, unfortunately for the apparently unaware laptop industry, I need to also work a little bit sometimes.
Thankfully Apple never jumped on the stupid 16:9 bandwagon with their laptops. Now if only some monitor manufacturer would wake up and start making 27"+, 16:10, 4K+ monitors with 120hz+ refresh rate then I'll literally instantly buy 5.
This is not entirely true :) The MacBook Air 11" was 16:9.