These different profiles are all available from within the application, but the widgets earn their place on desktops by reducing the number of clicks to select them. If you are an advanced enough user to understand why you might want multiple profiles, then you will probably appreciate the convenience of these widgets.
At a time when applications in the cloud are trendy, KDE offers another model, incorporating social applications into the desktop environment. Both the Community and Social News widgets offer a quick connection to the KDE-centric openDesktop.org, while Knowledgebase allows you to search the KDE online help. All three were among some of the first social widgets in the KDE 4 release series.
However, they are far from the only ones. KDE also carries widgets for Microblogging, as well as a connection to Remember the Milk, the online task list. Similarly, you can figure the sources that display in the News widget, or search Weather Forecast to receive updates on conditions in many cities worldwide.
Technically, such widgets provide little that a link doesn't. However, they are better thought of as bookmarks that are more flexible than those in your web browser because of their high degree of configuration,
From the earliest days of free-licensed desktops, widgets have included toys. KDE is no exception, offering the classic Eyes, a pair of ovals with moving pupils, and Bouncy Ball, which careens around the screen. Such toys are taken seriously enough that Bouncy Ball includes a half dozen controls to alter its apearance and motion.
However, you might prefer slightly less frivolous widgets, such as Comic Strip, or Fifteen Puzzle, the classic game in which you have arrange tiles in order by moving one at a time.
If you are more studious, you can load Chemisty or KAlgebra to help with basic calculations in schoolwork, or the Kalzium Concentration, Gas, and Nuclear widgets, or the Molar Mass calculator. With these widgets, needless to say, you are obviously getting into very specialized small applications -- to say nothing of surprisingly powerful ones.
To some, many KDE widgets may seem too trivial to be worth writing about. Really, though, they are an example of how the whole can be greater than its parts. Depending on which applets you load, you can have a very different desktop.
For example, load the educational widgets, and KDE becomes a practical desktop for a science classroom. Load the hardware indicators and perhaps the Network Management and Konsole and Kate profile widgets, and KDE transforms into a graphical interface for light system administration work.
The fact is, widgets strongly affect how you use KDE. If you want a classic desktop with application launchers, then you need to use Folder View. Moreover, several of the templates for Activities, including Newspaper Layout and Photos Activity, vary largely by which widgets they include by default. You might also say that, without widgets, much of the point of having Activities in the first place disappears.
However, you don't have to use KDE's more advanced features to appreciate widgets. Even if you prefer to use KDE in a very basic way, you can probably find at least three or four widgets to make your daily work easier, if only by reducing the mouse-clicks for common tasks. And, once you are used to them, you understand why omitting them makes Unity and recent GNOME releases less compelling.