I installed a fresh 5.4.2 plasma and found no obvious way to show the desktop, i.e. get all windows out of the way to reach the desktop. Suggestion: add the "Show desktop" widget to the default panel.
Thanks for the feedback. I can see why you might want it, problem is everyone has their own unique opinion of what plasmoids are useful to their workflow. If we added all of them we'd just end up with everything. Currently this can't happen. show desktop is part of kdeplasma-addons. Naturally anything in "addons" can't be in the default setup. I will look out for others saying the same thing in future, and will revisit this if feedback indicates we should.
Thanks for the explanation, David. On the one hand, most of the users who switch from MS Windows would miss a Show Desktop functionality. But as you say, there are other valid opinions. I would like to solve this conflict by adding a feature which is known from other complex applications: an option to choose different default settings from a list of other often-used desktops where users might want to migrate from (e.g. Window 7, MacOS X). Such a default setting could affect the default panel items (e.g. have a Show Desktop item for Windows 7) and also keyboard shortcuts (e.g. have Meta+D as shortcut for Show Desktop). Would such a feature generally fit to the current plasma philosophy?