My theory is that un-released software is like physical inventory. Keeping inventory is very expensive because the money spent could have been earning interest elsewhere and product sitting in the warehouse becomes gradually obsolete. As you accumulate a great deal of software inventory towards the end of a big project the cost of keeping the inventory, and therefore the pressure to complete the project, naturally increases. Shipping small increments frequently and not keeping much software inventory is the most efficient process if the product design/market allows. (I'm not saying this is always possible or would have been appropriate in this case, just making a comparison.)