GP here. It's 12M because the displays are square, not 16:9, so there are more vertical pixels. This will look better than most existing headsets, but it's not enough to match flat displays. You can't think about it in terms of traditional monitors- this is 4k over your entire field of vision, which translates to monitor-sized objects at maybe 720p. That's why all the virtual screens in their demo are so big; they're very low density.

Remember the age of 768p laptops? It'll look like that.

I get what you're saying in a mathematical sort of way, but I think the point you might be missing is that "monitor sized object" isn't a relevant concept for this device. You're saying that I can't think about this in terms of regular monitors, but I think you're doing precisely that.

"monitor sized object" exists as a thing because we live in a reality where desks limit the size of the things we can reasonably use for work. But here, your desk is virtual now. There is "space" for a bigger screen. You're saying they compensated by making the virtual screen larger--my thought here is "so what"?

Text legibility / crispness will be important. I'm one of those guys who buys the 5K displays, so I agree it matters. But Apple made a point of calling out clean text rendering, and none of the previews have complained so far. But obviously no one in those early previews has spent 8 hours in an IDE, so we'll see.

Fully agree that more would be better, and would increase the usability of smaller, more fine elements. But this might be enough resolution to pull off the concept in a perfectly usable way.