Don't agile approaches encourage this, focusing on features and things that can cleanly be assigned story points at the expense of a bigger picture, with velocity being the focus?
If the spec is not wrong, careful planning is probably better than high velocity iteration.
I think cryptography is a good example of this--would you develop a cryptographic API on which people's lives might depend iteratively through a release early and fail often method? I hope not.
In a lot of software development, especially large scale enterprise software (where you're trying to map a complex set of existing business practices and workflows into software) and embedded software (where you have to write something that provides fixed, well-understood functionality running on hardware with a months- or years-long iteration time) you do have a complete and correct spec (or at least the means to generate one). In these cases a less ad-hoc approach than Agile can be beneficial.