Because it's much faster if I can select the related files in the explorer and select "Show Log", just as I would for single files.
Of course, the suggested functionality is already available, but it takes much more time, and it lacks some comfort which I am about to put in another suggestion (add option "show only filtered files" in log view): I would like to be able to see only the files in the lower pane that I have selected in the explorer.
In your suggestion, the "show only affected paths" will reduce the file list to only those files from the selected folder, but I need to scroll up and down and search for those files (in red) that I have filtered.
The "Show Log" on selected files/folders on the other hand could directly use the
"show only affected paths" to show only those files in the lower pane of the log view that I selected in the explorer.