Apple worked out they were selling macs with a and a 5K screen to cheaply, especially if you got the cheapest build option, also with white bezels on the new 24" inch and lots of colours its now more of a consumer home computer, its meant to look easy on the eye, the light bezels means it blends into lighter walls more easily and its a computer that is used by a family, not a pro machine any more as it stands.
Apple also worked out they could make even the mac mini a powerful little desktop with the Pro chip and they can sell a 5K studio monitor at a price they love that makes most people cry. So the 24" iMac was born. It is not really in need of being updated as much, in fact Apple desktops don't get new chips as often as macbooks.
What I dont understand is why make it so damn thin, I mean a 3.5mm headphone jack is deeper so it has to plug in the side which personaly I think looks ugly, but as a family machine its great and is not dominating to look at. I guess it blends in due to its colours and it's lack of bulk helps. People who need more power go to macbooks, mac Mini pro's or Mac studios etc.
I really don't see a 27" or bigger iMac coming in at the old prices as the Studio monitor and Mac Studio replaced the 27" iMac, and if they make a 32" M3 Pro or whatever the things will be called its going to be really expensive, more expensive probably than the iMac Pro. Also its a very niche pro market for a screen that big. I bet Apple if they decide there is a market for a screen that size will make it a stand-alone monitor again, and then you plug in your computer of choice. I hope I'm wrong but I think the days of a big AIO iMac are long gone sadly.