3:2 and 4:3 used to be fairly common but I think economies of scale made everything 16:9 because of TVs

Fortunately 16:10 is becoming more popular again which does give a bit more vertical space

It sounds like people in your workspace haven’t discovered opening multiple windows side by side.

I’ve found people in the windows world often make everything full screen all the time- such a waste. You have a 40” 6k display and you open a single giant word doc.

You could have 3 or more documents open side by side- or a webpage for reference, a notepad, and your work or 1000 other combinations.

I do development work so my workflow is extremely text heavy, but it’s rare that I don’t have 4+ windows open simultaneously per display. I also use an old dell monitor I had laying around rotated 90 degrees as others mentioned for log monitoring or chat threads.

I think people just need to get more creative using their space- it’s not the monitor’s fault if you don’t fill it with stuff.

the most commonly used workplace productivity apps are less useful in landscape mode.

They aren't less useful, they just don't take advantage of the extra space on their own. A wide monitor allows you to put multiple windows side-by-side without the expense of an additional monitor though.

With that in mind; a wide monitor is useful for document editing, web browsing, media viewing/production, gaming, and can even be rotated (stand/mount permitting) for a tall view if desired.

A square monitor is much more limited.

The market is to optimize for max human eyesight, which is a horizontal aspect ratio. For edge cases, a monitor can be converted to a vertical aspect ratio easily.

There really isn't a large market to go square. If anything, monitors have gotten wider over time.

I am a big fan of 21:9 aspect ratio because it is wide when you want it but can be square(ish) when you don't by snapping two windows sode by side.

We did that for decades. It was pretty miserable.

I still have one of these at home

I think it's 5:4

I suspect the answer is because computer monitors evolved from televisions and video monitors, which standardised on 4:3 and, later, 16:9 for media viewing.

There was a brief period during the switch to LED when 3:2 and then 16:10 looked like they could take over, but 16:9 made a comeback and monitors have remained mostly in lockstep with modern TVs ever since.

Humans (and most other animals) see better side-to-side than up-down. Your eyes are spaced horizontally, giving us a wider horizontal field of vision. People generally prefer putting things side-to-side in work environments, maybe also reflecting how much easier it is to move and work within a horizontal plane than a vertical one. So the upper threshold for monitor width would be longer than the upper threshold for monitor height.

That being said, I know reading is best done in narrower columns, to reduce the amount of left-right movement your eyes need to do which can cause you to lose your place when skimming lines. Three columns of text on a 16:9 monitor is way more readable than one column of text that spans the entire monitor.

And then why do we make an exception for phones which are predominantly used in portrait mode? I guess maybe just for easier 1-handed use? Maybe also to give us more peripheral vision of potential hazards and other things happening in the background when using them, since they're mobile devices.

We see on a wide horizontal plane, so maybe there is a connection to that?

You turn your secondary monitor 90 degrees and rotate the screen in display settings. This is how I worked on long list items.

I imagine it has to do with binocular vision. If each eye sees roughly a circle, overlapping roughly makes a landscape rectangle. So perhaps that aspect ratio and orientation just "feels" better?

Modern squarish (16:18) monitors do exist, a friend has one and swears by it. For example, this one isn't even that expensive given the size, resolution and that it's bundled with what looks like an excellent monitor arm.

Personally I'm more in the "two windows side by side on a big ass 16:9" camp.

A 16:9 screen is basically two squares side by side, so instead of making a big square they can just make the landscape monitor bigger until it's large enough that you can comfortable view two documents side-by-side. I definitely prefer 16:10 or 3:2, though.

Nothing would look good on a square monitor.

If you want a tall monitor, turn it sideways.

Remember when PSUs used to have a power port in it that you plugged your monitor in to?

That was a great idea and wish it still existed but I guess they needed all the space for all the millions of peripherals that got added.

I tried for a while to use two 16:9 vertically. Like you say, vertical makes a lot of sense and it works great. But web devs seem universally to assume that if it’s a tall narrow screen, to show the mobile version.

It’s easier on your neck to look side to side than it is up and down. So to get more screen real estate it makes more sense to go horizontal. Anecdotally, I constantly have two documents or a document and a web page open next to each other on one monitor. The landscape framing works really well for that.