Had to lock the thread just to keep it organized in there but feel free to discuss it here.

I think CCI alluded to the costs even on days they are not holding events so that they can reserve the area. Otherwise they'd have to set up, take it down and then repeat the whole process again the following week.
On the other side of it, think of the costs for exhibitors. The major studios will be fine but mom and pop comic book stores? They'll struggle to basically shut down for 2 weeks in order to set up shop. Sure, they could just choose 1 week and other vendors can step in but then you start to run into problems of not offering the same experience both weeks.
Then you start to look at the panels. Would the programming be the exact same both weeks? Would studios be able to bring the cast, et al? If the programming varies, then you'll just have people buying badges for both weeks and create the same demand.
And lastly, look at it from the costs for attendees. Hotel prices are expensive enough as is. Extending it longer would put a total strain and take away from the con experience.
I think people look at Coachella breaking up into 2 weeks and assume Comic Con could do the same but I think the logistics of it and just the nature of the 2 events are so different that it's not something that you can just say, okay, let's do it and it'll resolve all the issues. It sounds like it'd create even more issues in my opinion...