Diversity and monoculture in software development

Esther Derby makes a good point about monoculture and recruitment: hire people who are too alike and the organisational meme pool shrinks. As it shrinks, recessive memes start to dominate individual and group behaviour, and before long a monoculture is established.
But while I agree with what she says, I think that monoculture is endemic in software development for reasons beyond just recruitment. Monoculture emerges very quickly in software development teams that impose a 'standard' IDE and OS, that use a predictive (not adaptive) lifecycle process, or where developers are expected to work the same hours on rigid pay scales in cube farms while adhering to a dress code. The recessive memes in these organisations are expressed in beliefs such as "all projects are the same", "developers are irresponsible" and "we know what the users want without needing to talk to them".
The first sign of a monoculture is often the absence of dissent giving the superficial appearance of order and control. Whereas an organisation with a healthy level of diversity can appear to be on the edge of chaos. This is certainly the case in companies with an agile software development culture: one that is goal (not task) oriented, encourages interaction and feedback, allows self-organisation, leverages groups (not just individuals), and values experimentation. These are the conditions where diversity thrives.