We don’t need to have everything explained by the film. There are other non-film sources with which to draw on for relevant information to people who would care.
Those other sources aren’t canon.
Actually, yeah, they are. Unless they were published before the Legends EU rebranding.
I am pretty sure the novels are not canon. If they are, explain the differences between the novels and the movies.
The novels are canon - http://starwars.wikia.com/wiki/Canon#2014_reboot
well dialogue in the novelizations of the movies better match with the movies word for word or you’ve inconsistency. If the dialogue differs what did the character say, what is written in the book or what is said in the movie?
example ROTJ
in the book the Emperor says “Your puerile skills are no match for the power of the dark side”
in the movie the Emperor says “You feeble skills are no match for the power of the dark side”
yet both sources are canon. So which did the emperor say?