I'm totally with you on this. Many things in technology have slowed down in terms of improvements ... and where else to better spend the money than on the device you look at for several hours a day.Regarding expenditures like this, I primarily write software for a living, but no matter what I do to earn money these days I'm largely staring at a screen.
So it is not as hard for me to make an investment in a monitor. I think it has a lot to do with what you value. People spend a ton on cars that depreciate badly and are mostly needed to commute for work, people don't take issue with this---its almost encouraged. These things sit idle most of the time and often require financing! So a super-high end monitor you stare at constantly seems a lot less crazy to me.
I actually think this whole thread is driving at something I've noticed which is that Apple has no display products for developers. The best they have right now is the LG screen and with the gloss and build quality it is just not amazing.
I'm actually looking to get the LG 5k anyway, (I use the P2715Q currently), though really what I'm hoping for is that Apple will announce a new mid-market cinema display focused on developers at WWDC. I thought I'd link out to that since there's clearly a market void in display tech for people who prefer Apple product quality.
I had one other note for this thread which is for developers I think PPI is crucial. Color and contrast can't make up for low PPI when you're looking at fonts all day (and night). This site, Pixensity, is the best I've found for tracking the highest PPI monitors available. It isn't pretty but I think the data is still up to date.
Looking at the top 10, you can see that higher PPI monitor product release has been pretty stagnant for while. Also the XDR's PPI is surprisingly beat by the Ultrafine 5k, though not by much.
If anyone is aware of a better site for tracking PPI please post.
I really don't find the PPI on the Ultrafine to require more improvement for me, however. Even now I can scale to basically any resolution and the loss in quality due to non-integer scaling is not an issue at my normal viewing distance.