It hasn't come up here (at least as far as I have seen) but on TripAdvisor there are lots of questions in the Air Travel Forum regarding having one's middle name on the boarding pass. The answer has pretty uniformly been that it is not necessary for English language names, unless perhaps one has a first name like Mary Anne, etc. But two days ago there was a major dust-up at the Toronto airport when WOW airlines denied boarding to a number of people whose boarding card did not have a middle name. The reason given was that the name on the boarding card did not match the name on the passport.
http://toronto.citynews.ca/2018/04/09/no-middle-name-ticket-keeps-mississauga-woman-off-flight/
Some of the responses on TripAdvisor suggest this was simply WOW Airlines way of handling an overbooked flight without paying compensation. The airline said it was required to do this under applicable air travel regulations.
I am wondering if this is an isolated occurrence, or maybe the start of a new requirement? I have not ever used middle names on our international flight tickets. I don't recall there even being a space to enter it on the booking form. Does anyone here put theirs on the ticket?