I was not really discussing whether or not it should be done that way. Of course a fixed location isn't the best way to go. It's just that on the web, huge problems can take years to get fixed, so nobody will ever care about something that is merely inelegant if that thing already works. That's why I think there's no way this proposal would get any support.
If there were a proposal made by a serious industry coalition (including Microsoft) for an improved icon standard (Maybe associated to some sort of website description microfomat metadata semantic web 3.0 thingie), it could get fixed, but only as a replacement for favicons.