I recently encountered an unfortunate side-effect of the custom of
not allowing laypeople to see the Vinaya.
I came across an excellent English translation of the Chinese
(Dharmagupta) Patimokkha, which i was very excited about including
in sutta-central. But unfortunately, it was translated in Chinese
temple, so making available for lay people was an issue.
A shame, for it showed in brilliant clarity just how close the
Dharmagupta Patimokkha is to the Theravada, and thus, how similar
the roots of the monastic traditions are, despite differing
appearances and practices.
One of my 'other' jobs is forming a body called the Australian
Sangha Association, bringing together Buddhist monastics of all
traditions, and i have been repeatedly pleased at how the various
traditions all regard the vinaya as a core aspect of our shared
committment to Dhamma.
Another related problem is bhikkhuni ordination: traditional
Theravadins remain opposed to this, partly because they often
believe that 'Mahayana' monastics are not really bhikkhus and
bhikkhunis (if they are even Buddhists). Only ignorance of the
closeness of the monastic codes can sustain this belief - especially
in view of the fact that Chinese bhikkhuni ordination stemmed
originally from Sri Lanka!