When I see something named "Making of <movie name>" what I would expect is to see a documentary which tells how the movie was made, as the very name implies.
In other words, I expect to see interesting tidbits about the preproduction, production and post-production of the movie. These could be things like actor screen tests, walkthrough of the stages and filming locations, "third person" videos of filming of some interesting scenes, showing how some stunts were made, how special effects and computer graphics were made, etc, etc.
Sometimes these documentaries actually contain some of those things. However, more often than not these "making of" documentaries are simply lengthy trailers of the movies with some interviews and commentaries here and there. Instead of telling how the movie was made, they instead tell what the movie is about. Typically someone explains in great length the basic idea in the movie, while short clips of the movie itself are shown. Sometimes some actor/actress is interviewed and he/she describes the character he/she is acting. In a few cases some really short clips might be shown about the actual making of the movie, but that's all.
I don't understand that at all. What does that kind of extended trailer have to do with the making of the movie? It's just a trailer with commentaries and interviews, not a documentary about how the movie was made. Most of these "making of" documentaries are clearly aimed at people who have still not seen the movie. In other words, it's a trailer.
I would expect a true "making of" documentary to be aimed at people who have already seen the movie and are interested in knowing how it was made. However, most of these "making of" clips fail completely at this.
Why do they call them "making of" when they clearly aren't?