It seems that people repeat adding new items a lot in the shader editor. To do that, one would press Shift+A, and then S to search. (There are so many items, that manually navigating to the submenu is not very practical.) There also is “Add” menu in the tool bar, but one would click “Add” and then “Search” to begin searching. That’s two clicks.
But can’t it be more convenient? There is a large empty area on the toolbar between the pin icon and the up arrow icon. What if you add the search bar there, so that one could just click it and begin searching right away, and then press enter to insert that item?
Something like this:
PS: Come to think of it, there is an even better way. How about showing the search box when one double-clicks anywhere on the empty area of the node area (background)? Then, Blender can add the new node where it was double-clicked. These days, a lot of applications use this semantics: “double-click empty area to add a new item”. For example, in VS Code, double-clicking on the empty area of the tab bar adds a new document. In Gimp, double-clicking on the empty area of the window shows open-file dialogue. So, this would not be a weird behaviour.