It seems like Bethesda had plans for a very different ending for Fallout 4, but somewhere along the way decided to change direction. Thanks to some people that have datamined the game, hidden sound files have been found that reveal another version of the story that probably would have pleased more gamers.
To avoid absolutely horrific spoilers here, we're not going to tell you about either the real or alternate ending here, but if you already have completed the game and would like to kinow more about this - head over to Tumblr for a more fulsome explanation.