As the author of the article on Duncan Lewis (AJ 14.4.05), I would like to thank you for drawing attention to his work in the editorial. You are right to emphasise the bricolage aspect of his work - it is a very important aspect of it, particularly when you see the buildings up close.
It is something that I've alluded to at times, but have downplayed for British consumption, precisely for the reasons you outline, but also because the bricolage aesthetic too can become a style and an affectation. Lacaton & Vassal, for instance, has staunchly resisted the label of Arte Povera architect.
For the social housing at Mulhouse, the material finish is much neater (probably influenced by Lewis' associates on that project, Block Architects), and at Fredrikstad the level of precision is higher, due to its northerly latitude. So the degree to which 'bricolage', camping, grunge, etc, is at play and how it is played out is always a question of native circumstances - of what the site and the given materials will allow.
Robin Wilson, by email