Kubuntu has the hotcorner bound to "Present Windows" in the top-right corner of the screen. This is sub-optimal because it means that people often trigger the hotcorner by accident when they're trying to click on the a maximized window's close button. We should move the hotcorner to the top left corner instead.
'Often' is probably an exaggeration, since the recent reddit comment is the 1st time I can recall anyone complaining.
It was moved because at the time with that Plasma release the hot corner zone and the toolbox both conflicted with being able properly use a top-left desktop icon such as home/trash.
In Plasma 5.13 on fresh installs or newly created users on and existing install, there will no longer be icons on the desktop by default;
so we can certainly look at reverting our placement in Cosmic and backports when 5.13 lands.
I don't think in practice it would be a problem to have the hotcorner separated from the Desktop Toolbox button. I wouldn't be in favor of moving the Desktop Toolbox patch to the left again because it's always supposed to have been be on the right with RTL keyboard layouts. Only a bug was preventing this, which has since been fixed upstream; when we revert our patch for the 5.13 timeframe, the Desktop Toolbox will remain on the right.
The problem with the hotcorner at the top right is that it interferes with your ability to quickly click on the close button when a window is maximized or tiled to the right. If we moved it to the left, it would only interfere with your ability to click on the app icon in the titlebar, which I'm willing to wager is clicked on several orders of magnitude less frequently than the close button.
(all of this assumes default settings, of course)
"You can change it!" is not a helpful comment in a discussion about defaults. The whole point of good defaults is that they should work well for the majority of people and use cases without needing to be changed.
The whole point of good defaults is that they should work well for the majority of people and use cases without needing to be changed.
That implies you'll have to ask the majority. What is the actionable path here?
You don't have to ask the majority to determine a good default. That's the job of a good UX designer, using the skill of empathy.
The actionable path forward is to determine whether or not to move the default hotcorner to the top left.