When Disney studios purchased Lucasartfilm, they essentially canceled all the books, tv shows, comic, movies.. etc. As of moment of purchase in May of 2012, only original six episodes and (2008-2014) Star Wars The Clone Wars were left canon. Now they are creating a single timeline using books, comics, new movies, and tv shows. Quite frequently they are cherry picking some characters, vehicles, locations, concepts...etc. from the expanded universe, that is now considered Legends. It is just make sense that a lot of Lego sets at the moment are not considered canon anymore, as it will never be or just have yet to be introduced into the canon timeline. For example, the entire line of sets based on the Old Republic is not canon, as The Old Republic is not part of the Disney "canon" timeline.