Currently, KDE doesn't have any official way to easily format usb sticks or usb devices without needing to open the whole extremely complex UI of the partition manager. While the current partition manager is very useful, and we should never give up on it, it could have a simple UI by default, with a button somewhere to switch to the "advanced UI" that would show what it is now. This simpler UI would be much easier for new users when they right click on "Format device" in Dolphin, and they expect a simple app like the one that appears in windows when you want to format something. This simple mode UI would not have partition editting, and would instead always format the whole drive into a single partition with the chosen filesystem and label. The filesystem list should also be minified into only a few most used ones, like extfat, fat32, ext4 and btrfs. All others would still be available in the advanced UI mode. Many distros avoid pre installing the KDE partition manager because they find it too difficult for casual users. They instead pre install gnome-disk-utility, which in my opinion is easier to use but at the same time does not fit KDE at all since it is a GTK app and is also not very easy to use, still too complex when all a user wants is to format a damn usb stick. Having these two UI modes in partition manager would immensely help newer users without removing access to any functionality from advanced users. The simple mode should be the default when opening this app via the dolphin "right click on the device" shortcut. This dolphin shortcut should maybe be changed to two shortcuts, one called "Format device" that would open simple mode on that device, and other called "Edit or change partitions" that would open the advanced UI, similar to what it already does right now.
I just found out that a simple formatter app like this already existed 15 years ago but is completely forgotten by the KDE team (probably). Its called quick usb formatter: https://store.kde.org/p/1127650 So all we need is to revive it and integrate it with Dolphin.
This is generally a bad idea; see https://community.kde.org/Get_Involved/Design/Frequently_Discussed_Topics#Basic/advanced_modes In general, the desire for this is a sign that the main UI itself could use some design improvements and simplification (NOT feature removal! those are different things). Allowing USB disk formatting from Dolphin would be another approach to take, yeah.
Yeah, I think a completely separate application is a better idea. It could very well re-use kpmcore library but there is no point of sharing any code in the UI repo.
That's another option, yeah. Let us know in the VDG if you'd ever like to see any mockups for a visual overhaul of this app to make it a bit more basic-user-friendly!