1. it is too fat, and cannot lose another pound 2. the Navy does not want any aircraft with a single engine 3. it cannot carry enough fuel to perform its primary mission at acceptable performance levels 4. we don't need it
I know a little about the design. Some of the electronics had to move to mitigate gunfire loads, some of the sub-contractors took a lot of time to accept the "economy of scale" mandates, etc... so flushing out weight is just now being worked.
Typically, Designers concentrate first on getting systems to work. Bench-testing (for lack of a better term) eventually proves a design and the weight is attacked later.
I agree "later" has come; I disagree there is no margin. While there are critical areas fat, there are other areas still to trim. I don't expect weight issues to be resolved anytime in the next 12-18months.
The Navy didn't want on board from the start, right? ...as I understood it. But they continue to be present, talking the details at every review.
I'm not privy to the fuel situation; is this a product of being overweight or poor engine performance?
I guess they solved the weight problem:
http://biz.yahoo.com/prnews/040914/datu033_1.html
http://www.airforcetimes.com/story.php?f=1-292925-354931.php
http://www.dallasnews.com/sharedcontent/dws/bus/stories/091504dnbusjsf.188b7.html
It looks like it will happen.