I read through most of your thoughts, and the first thing that pops in to my head is 'overhead', 'bureaucracy' and 'little kingdoms'. However, this part I can totally agree with, because I suspect I simply have trouble seperating the basic ideas from the exact workout, and I'm unsure how much of this overhead, bureaucracy and the creation of little kingdoms (if at all) would be caused by the core principles of your thoughts, or by the way they are worked out. 

With a proper real life discussion (be it at Wikimania, or elsewhere) we could go more to the bottom of it, and figure out an approach which has a positive impact on the overhead etc (for example, by indeed reducing the work for the bidding teams - something always stated as a goal, but so far only the reverse has been the practice) and on the outcome (a more effective wikimania). 

However, there is one thing we could perhaps start discussing first, and that is defining what we want to achieve exactly with Wikimania. What are the goals? For example, if maturing the local team organization is one of the main goals, then a different approach might be required (focused on training rather than taking over work) than if the only goal is to have a big wiki-meetup. If we want to have tangible outcomes, the whole structure might have to be different than if we want to have a big networking event. Etcetera. 

Lets figure out where we want to go with Wikimania, set up this Wikimania committee, and work from there on a more detailed structure (for example, during a dedicated session(s) at Wikimania 2013). I'm afraid that if we jump to what kind of teams we need etc, we're skipping some very important steps. And taking a step back is often much harder than going a bit slower in the beginning. 

Best,

Lodewijk