"Why are Microsoft and Apple the only manufacturers that can grasp that for a professional user having a screen optimised for movie watching is just stupid?"
Last time this came up it transpired the real complaint wasn't aspect ratio. It was lack of 1200 px vertical resolution for someone editing text on a single, presumably not very wide document and would like more lines. That's one use case. Just one.
Transcribing text from images - two documents, image and text side by side
There's a whole load of applications which all benefit from a wide screen.
Yes, by all means complain that you'd like more pixels. But if, as here, there's an option of a 4K screen that complaint really won't wash.
Then there's the simple observation that for a typical laptop the screen matches the width of the keyboard. If it doesn't then you just have a couple of black panels either side of screen utterly wasting space that could be put to better use.
Why is that? Look at the average keyboard. It's wide. As far as I'm concerned narrow keyboards went out about the time the VT220 replaced the VT100 - mid '80s IIRC. So, if you have a reasonable keyboard layout and make use of the width that implies, how are you going to fit a full width but still 4x3 screen above it? You are going to end up with a massively deep back to front piece of kit that nobody, probably not even yourself, wants to carry round.
As far as I can see the only way you're going to have your 4x3 ratio screen without wasting space on either side of it is to go back to using one of those dumb keyboards that reuses some of of the letter keys as a numeric pad.
You don't believe me? Try laying out a laptop design that fits your 4x3 aspect ration, has a decent keyboard, is a size and shape you'd be preared to carry and doesn't waste real estate under the lid that some of us could usefully use for pixels, even if you don't want that many.