I think the part you’re missing is the screen size in theatres. I saw The Odyssey in two formats (70mm normal film, and Dolby Cinema).

In both theatres, the screen and image took up the nearly entire height and width of the theatre. The image filled the screen. The 70mm theatre I saw it at had a very wide screen, but not very tall. Filled the wall though

So even if it’s possible to project a digital version in the 1.43:1 aspect ratio, you’d end up with severe cropping on the edges.

That’s not the point of this IMAX format.

The point of this IMAX format is to have a screen that’s literally twice as tall as those normal screens. To accomplish that, you need a really, really big room. Most theatres can’t physically fit these screen sizes. That’s why 1.43:1 IMAX is so rare compared to 1.90:1.

So when you see it in a theatre like that, firstly the image is really big. But the main thing is that the image stretches past your peripheral vision vertically. In fact, at my local one (which recently shut down, no Odyssey), you can’t even see the bottom of the screen, just a slight curve at the edge of the floor. Which doesn’t matter because the image is framed to not put important info there. The point is for the image to be bigger than life.

Showing a cropped version is just not equivalent to that. You could argue that we should have the choice. But I think generally because of how it’s framed, I’d rather it just take up the full size of my TV. So IMAX releases sometimes come out 16:9 instead of cropped top and bottom.