I would hope more scenes with Anne Hathaway were filmed. There was so much moret o Fantine that could be explored, as we only see her from when she is working at the factory, to when she sells her hair and then to her sad death.
I understand what you mean, but can't see how they can do it. The problem with musicals is they live and die on the music. The longer the gaps are between the songs the more the songs start to disrupt the flow of the film IMO.
Unless you are really engrossed in the story or engaged strongly with a character it's very easy to start wishing they hurry up to the next song as it's getting a bit dull.