Some other suggestions:
1) Not understanding that "Lean" methodologies don't apply to knowledge work. I work for a manufacturing company, and our executives don't understand that Lean processes (which don't work all that well even in manufacturing) aren't applicable in knowledge management, where you *need* excess capacity. Information and knowledge can't be provisioned in real-time unless you've created an environment in which information and knowledge are continually generated, stored, transmitted, and reused.
2) Underspending on IT. Most non-technology companies spend around 4-5% of gross revenue on IT, and technology companies spend 15+%. My company spends less than 2% of gross revenue on IT. This means we can't accomplish much of what the business needs us to do, which makes IT increasingly irrelevant to them. This, in turn, provides justification for the business to reduce IT funding, which ratchets the spiral downward.
3) Fostering a culture of "Shadow IT". As IT becomes increasingly irrelevant, business units are forced to spend time and resources solving the same problems over and over with different choices of technology and different business processes. Slapdash solutions, poorly implemented and negligably supported, proliferate across the Enterprise. Data is stuck in application-specific silos, and economies of scale that could be leveraged from reuse of data, technology, and business processes are not realized. Feudalism reigns supreme.
Sic transit gloria mundi.