As a footnote to this conversation, I'd like to point out the aesthetic issues involved in using any standard image; particularly one who's purpose is replacement. Certainly it cannot be pretty, as such would be pleasing and therefore incongruent to the purpose of replacement. The current image takes this into account and is indeed quite ugly, I don't think its particularly ugly enough to make people want to replace it immediately.
Perhaps we can have a contest to produce, within suitable boundaries, the ugliest possible image with the utmost of replaceable qualities.
-steven