I understand that many everyday users may prefer a keyboard interface because almost every search operation needs it. However, sometimes (except you use CLI) mouse is necessary. One such case is the filter menu: you have to select (from the menu list) one (and only one) of predefined filters.
And there are two questions:
1. Why I can't do it with a single click?
2. Why that only one category of objects can be displayed after applying predefined filters? Why I can't see for example both folders and executables?
The reason for these limitations is just the selection mechanism.
I would suggest that each of these filters have a separate flip-flop button (plus an all-off action button) and the user could include all categories set on. This would speed up the use of filters and improve the feedback (buttons set to "on" would be easily distinguished).
The current filter list would be reserved for private filters.
GUI is too simplistic
Re: GUI is too simplistic
After enabling Menu:View > Filters, the filter bar will be shown next to the search bar. Here you can select your filters too.
Or right-click the status bar and select the filter you want to acivate.
There is no overlap; they are largely mutual exclusive. A folder can't be an executable; there will be no pictures shown when the Audio filter is active.
You don't have to select filters from a list; you could also type - for example - audio: in the search bar instead. This way you can combine filters.