One example of the shortcomings of emails as a medium for complex discussions is how this thread about postmortems continues to be diverted into discussions about Facebook, despite Pete's best efforts.
At the end of the day, people will prefer tools that work well over tools that align philosophically. One can sabotage the development of tools that would both work well and uphold Wikimedia's values, but cannot prevent important discussions from moving to other venues (which will necessarily be a worse match for those values). There is a lesson there, although I'm afraid it will take some more time before we learn it.