> the characters there do not seem that much at odds with the book or the first three movies

well, The Hobbit itself as a book is at odds with LoTR, being a children fairy tale rather than an epic.

Just compare the scene where they get away from trolls in The Hobbit with the the trolls attacking Gondor in the movie. The change of tone is insane.

OTOH, it's pretty silly to be angry about it :)