When a lot of books follow the same model there tends to be too many similarities, with some predictable lines and actions that the protagonist makes. This can lead to some people not enjoying a book or movie due to the fact that they know what will happen or knowing that everything will end up okay and happy in the end. This can give the author the opportunity to make
a twist that can surprise the reader. Not many authors kill off the protagonist because they want to please the reader, if the character is enjoyable. The use of killing off the character and then them coming back to life is also overused; if you were to kill them off then bring them back after a long time has passed in the story it would mix things up and possibly make it more interesting.
I believe that the hero’s journey shows up in almost everything that has a plot because to have an actual plot (the majority of the time at least) you need to have a problem or conflict and some sort of growth within the main character. If there is no real conflict or something for the protagonist to surpass it would just be a story of everyday life with no problems for the ‘protagonist’. If there is enough problems or realizations/epiphanies that may be an interesting story, Why would you want to read about something you could easily do yourself, though?
A lot of the time the main character starts out without any parents or family. I think that one of the reasons is to either set them apart from others or make it so it would be easier to leave their old way of life. Some authors tend to just throw romance into a story just because. I think if there is a relationship it should help the protagonist move in the right direction or have something to do with the plot. If the story happens to be a romance then the counterpart should not be the perfect little girlfriend or boyfriend; they should be a believable character.