In my experience, people dont 'design' modules to only work without strictures. More typically, they dont 'use strict' because, and I quote, 'you just end up with lots of annoying lines getting in the way' (I had an experience somewhat like that today - the developers had a huge script with everything as a global. And to top it all, I gave him a function to do some parsing, which promptly broke when he removed all the 'my's' in front of the lexical variables. A stern talking-to then ensued).
...it is better to be approximately right than precisely wrong. - Warren Buffet