I believe it was said before that they don't release the official patch notes because there are certain people out there that would take advantages of the game if they knew what was coming.

One example would be people trying to take advantage of the market, buying up all of a particular component that is currently cheap pre-patch, then marking them up outrageously post-patch because of a new recipe being introduced.

In addition to that, sometime things don't always go as planned. In software industry, something get cut last minute due to what issue or possibly the whole patch being rolled back due to instability.