Thanks very much for all of this. It has been very helpful and a very enjoyable discussion..
I have to run but let me just put this thought out:
In order to release energy, the fission parts have to have more binding energy than the original nucleus (as in fusion: the binding energy of the product  fused nucleus  has to be greater than the original parts if the fusion releases energy). This is possible for U because the fission parts can both be heavier than iron so the total binding energy of the fission parts is higher (which I think is the short answer to the original question).
But isn't the reason the binding energies of the fission parts increase due to electrostatic repulsion? That is, there is a smaller negative electrostatic repulsion term in the binding energy equation for the fission parts compared to original U235.
Quote by Morbius
Yes  also discovered that if you make a mistake in a "tex" equation, and you edit it; the system doesn't reevaluate the tex expression after you edit it. You have to copy the entire post to an editor [ I use Emacs instead of Notepad because I'm working in Unix], delete the faulty post, and post a new reply using the saved text from the editor.

Now I understand why your posts have these extra carriage returns!! The system DOES reevaluate the tex expression, it just doesn't reload your screen. If you use the advanced editor it should reload it for you. Otherwise, just reload the screen in your browser and the revaluated tex graphic will show up..
AM