Here’s a half-formed one that was the basis of my side of the discussion with them.
Design generally operates at a different clock-speed, and generally evolves best over time when certain strata of it’s basis are moving slowly, such as the requirements, the code base or the context of use cf. “How buildings learn”, “Adaptive Design” etc.
Does the speed and diversity of open source iteration leave a designer – if they are involved at all – building on shifting sands?
Segusoland – a novel file manager seems to buck this trend, or at least suggest a new way forward in working with UI design in an open-source-context by establishing and publishing open-source human interface guidelines, to co-evolve with the code.
* I may just think Open-Source UIs suck due to my ignorance and lack of exposure to excellent open-source UIs. If you know of any, or wish to offer an alternative appreciation based on your wider experience – then please let me know in the comments!