Martin Fowler talks about avoiding common Scrum pitfalls. A refreshing read. But Martin is able to point out the root cause of most of the faulty adoptions in a single sentence:
When you just try to do the practices, and don’t adopt the philosophy, it’s not going to work terribly well.
We see this many times, when projects are transformed to be agile suddenly. Personally, I think that the agility is completely ignored during estimation. There is still a tussle between business interests, mutual agreement on estimation and what agile needs. The other reason? Perhaps adopting agile development to look trendy. This is where the philosophy gets completely overlooked.