It's not so much about the resolution, in my case I don't need 6K, not even 5K, for a lot of my design work 4K is more than enough, but the screen size definitely matters to me. If the standard for professional use back in 2005 was Apple Cinema 30", then today they should be at least at the level of two decades ago!
It's 100% about resolution and PPI.
Going from a 27" 4K display to a 27" 5K Display (whether its Studio Display or Studio Display XDR or another brand with IPS or OLED panel) is a huge jump.
If you're a designer for example, seeing typography on a 5k display or high PPI display (Like MacBook Pros/Studio Displays) is a huge + compared to 4K displays.
For a while I had dual 4k displays and dual 2.5k UltraWide displays (looked like a spaceship) as I waited for Apple to release new displays (I have 2 of the first gen displays) and it was such a pleasure to use 5K displays again for design work, I could never go back.
32" 6k for me is too much real estate as I work with dual displays usually, 27" x2 is perfect for me, but it has to be a minimum of 5K resolution.
I've had every Apple display after Jobs came back (except maybe the expensive Trinitron CRT screens from way back, although I saw it in person) including the 23" Studio Displays and 30". While for its time they were great displays, the PPI was really low especially for design work on the 30".
Display Technology has advanced but not to the degree I would like. OLED is still super expensive especially tandem OLED and it still doesn't hold a candle (pun intended) to miniLED (which is also expensive) which spits out crazy amount of NITS especially for HDR content (which I personally don't care about, but seems Apple does).
At the end of the day, technology like batteries, camera sensors, displays, whatever, is based on economy of scale. The more popular they are, the more people buy them, the more it will advance and get cheaper due to competition. The IPS display in the cheaper Studio Display is still good but its an iteration of 10+ year old panels from LG (most likely Apple still uses them). It's perfected to a T for what it is and still works well. Yeah they're not perfect blacks but who cares.
I would eventually get the new XDR displays but paying $7000 for dual is insane, I'd rather get a M5 Ultra and keep my dual Studio Displays. Hopefully a a few years from now miniLED will become more mainstream and prices will go down, but from what it seems, Apple is one of the only manufacturers using miniLED, most others use OLED (inferior NITS) so I don't know if we will ever see miniLED drop in price, since Apple doesn't push out that many displays as the whole industry does. So we will eventually see Apple move to OLED when it has good enough brightness and costs drop.