I just don't share your point of view. I think KDE Plasma screenshot utility has a decent UX. You just press Print Screen key and then either press Enter to capture the whole screen or drag your mouse to select a region and then confirm with Enter. It then opens your capture in a small window where you can save it or discard it. All extra buttons have icons that are clear and easy to understand on first glance and functionality they provide is useful and belongs in a screenshot utility. It's pretty decent.

Edit: Since we're talking about UX what do you think about Gnomes window management? If more than one window is open and one of them is maximized you need two clicks to bring the other one to the top. Every single time. Gnome user is pretty much expected to learn keyboard shortcuts to overcome the terrible UX. Most just install addons that bring back basic UI elements but the addon API is not stable and most addons usually need an update between Gnome versions which wears out developers which results in the Gnome addon repo being full of abandonware. I used Gnome as my DE for approximately a year before I realized that all the time spent trying to wrangle that stupid fisher price DE into any resemblance of functionality would be better spent on something more productive.