I too would like the quick switcher to be able to search within files, because sometimes I want to open a file but can’t remember the exact name of the note. I can easily think of keywords to use to search for it.
If I’m working on my laptop, then I usually have all panels hidden except for the note that I’m working on - I really don’t want to have to open the search pane, perform a search and then (using the mouse) select the note… it would be so much more convenient to do this using the quick switcher.
NOTE: To ensure the Quick Switcher performs well, I would suggest that by default it should only search titles. To perform a full text search you should start the search with a symbol (such as “!”)