There are quite a few 27" screen out there which are 4K or 5K (a lot of people won't notice the difference or need 5K).
The issue with non-Apple screens is compatibility which seems to have been sketchy-as-hell since the move to thunderbolt over usb-c. Whether its screens that don't wake from sleep reliably (I've had that with a number of LG screens) or resolution issues where they just disappear from macOS or the fonts are fuzzy, if you rely on an external screen, it can be a frustrating issue.
I've got a 34" 5K LG Ultrawide which is so close to being great.
But there's no built-in webcam (so I have my laptop open on a stand) and the speakers aren't anything amazing.
This morning, it failed to wake from sleep, even after unplugging the thunderbolt cable to the laptop, so I had to unplug the power to get it back on. Which isn't a massive inconvenience, but its still an inconvenience.
I think the new display is still a bit over-priced, but given the speakers, mics, webcam w/centre stage, expected Mac compatibility, how much is that worth to someone?