It's never an issue unless you make it an issue by yourself. Several people have done this with Japanese airlines in various FT threads and were then not allowed to check in, but that was their own doing for asking the airline in advance vs. just walking up and checking in as normal.

I've flown both CI and BR many times with no middle name. I've also flown out of both SGN and HAN with no middle name. I don't think I've ever had a middle name on my ticket in Mainland China either, so all of your examples seem to be non-issues for 99.99% of people.