The value of higher resolution is directly related to your individual eyesight, and the distance you sit from the screen. Each individual will be different and each person's setup will be different. So just asking about resolution alone is only part of the equation.
For me, my eyesight is a tad blurry, so a 32" 1440 monitor looks super crisp 20" from my nose. To someone with eagle eyes, I'm sure they'd see a noticeable bump on a 32" 4k, but I can't. Therefore, increased resolution is not a good reason to move to a 4k monitor. Things like brightness level, screen technology, curved vs flat, ultrawide, etc. might be.
I think the biggest argument to upgrade for most people will be moving from IPS or VA to OLED. I won't be able to justify the upgrade cost for a few years, but I'm really happy to see the new 32" OLED monitors coming out. That's the combination of size and tech I've been wishing for over the last couple of years.