I once had a real modernist boss: pencil bow-tie, red wine and a cigar – also used for pointing to drawings and with the aggravating habit of dropping smouldering embers onto waxed tracing paper.
I think the rejection of ornament began with a horror of the design standards displayed in the Crystal Palace but it grew into a belief, not unlike early protestant design, that ornament was ‘crime’. And, yes definitely, a natural outgrowth of the Age of Reason. Designers were enjoined to consult fundamental principles and to reject the authority of the historic styles.

For the sake of their health hopefully the modernists have now given up their cigars but still enjoy a ref wine!

I doubt if the the point applies socially or personally, and think the modernists liked cigars and red wine, but the rejection of ornament and love of ‘plain function’ seems Puritan to me. So is the enthusiasm for conscience-based decision making rather than the acceptance of any points ‘on authority’.

Still reading…

Stained glass used to be a very expensive product and still is if hand made and lead rimmed. You do see coloured glass in contemporary buildings but not nearly as much as ‘one might expect’. I suspect there is a (generally admirable) puritan hangover from the Modernist aesthetic which is affecting designers.

It seems to be a motif of church and state rather than secular?

Garden design has not been as technology-led as it might have been, although green walls and green roofs are of considerable significance.
I love stained glass. Why don’t architects make more use of it?

It would seem that glass replaced wooden shutters [ http://www.shutterscanada.ca/shutter_company/shutters_history.htm ]and shoji screens? [ http://www.rothteien.com/landing/interiors/tategu.jpg ]

Innovations in design came with advances in material science. Here is an example from the 12th century [ http://www.visual-arts-cork.com/images-pictures/stained-glass-augsburg.JPG ] and from the 21st century [ http://image.digitalinsightresearch.in/uploads/imagelibrary/nri/designbuild/features/ars-electronica-center.jpg ].

Developments in glass technology have had a profound influence on architecture but I guess the first uses of the new technology were to do jobs previously done in older ways. Gardens are less technologically driven then gardens but the influences are still there. It was not so long ago that the first green walls and green roofs appeared at Chelsea. They are now common but one sees more examples of them being used badly than of them being used well.