I think the main purpose of publishing the preliminary report is to reduce speculation and rumourmongering by stating what happened and eliminating certain causes - the main one being major structural or component failure.
This is done partly to keep all the other 365 crews and pax happy that there is not a serious fault with the aircraft so that they can keep flying it without fear. If you were Eurocopter, you would want to show as quickly as possible that your aircraft is safe and I suspect that some pressure is applied from industry onto the CAA in these cases.
There are some other safety equipment issues that could have been included in the preliminary report but I will wait for the full report before discussing them.