Apologies for the late reply. I feel a browser should not be "looking" for a file unless it was linked to it through the HTML (ie <img>, <link rel> etc etc) or if the user requested it. That's the way I feel a browser should operate, and webmasters shouldnt have to insert any file into one or every folder just to satisfy the demands of one browser. If the designer doesnt provide an icon, for whatever reason (and this reason could be more than "dont care"), a browser shouldnt have to poke around trying to find something that is not suppose to be used.
Another compromise would be BETTER CACHING of icons for a site. However that leads to other problems when you have multiple pages with different icons on the same site.