Why do we want a Wikimania? What is its general purpose? What do we want
to accomplish. Not quite the question you quote - although I know from experience that you do ask that question yourself.
I would have liked to see that discussion
We never have enough, but this discussion has been ongoing for at least a couple years now. :)
This is a good point and a number of bids (particularly, successful ones) have articulated some kind of vision about what their particular vision and goals are. The work you've linked to Nemo is very good!
However, there's not been much discussion about what the role of Wikimania is in general, or what its aims are. Are the aims the same every year? What do difference groups attending want to get out of the conference and what should the priorities be in meeting their needs?
I agree with Lodewijk that this is a conversation that needs to happen sometime.
Chris