Sam, I'm with you on this but I would say there is one over-riding cause of all project failures and that is a break-down in communication.

It doesn't matter if it is and analyst failing to extort the user requirements or the users failing to articulate their requirements. It could be management failing to consult juniors or juniors failing to warn management. At some point the communication chain breaks.

If I think back to the killer apps or applets that I have seen in 20 years in the IT industry they are all very simple in concept and execution though probably not in the execution.

1. PKZIP

2. GREP

3. Intellisense

4. REGEX

I know of someone who says that all you get for $60K of software is $60K worth of bugs!