What was the purpose of the scene where she gets the box with the doll? I know it was meant to represent the child she miscarried, but after the shocker of her opening the box, nothing else was ever mentioned about it. Who sent it? Why didn't they try to find out? Very odd. That was a scene that added nothing to the movie.
The purpose of that scene was to highlight the fact that she was losing fans and had created a very negative image. It showed that she was receiving hostility rather than sympathy during tough times.
That was the ONE and only incident showing Kelly's "unpopularity" - everywhere else people were turning out to welcome her, those who were interviewed (in the movie) were saying that they had faith she'd be able to come back, and James said her first show had sold out in 15 minutes. That doesn't exactly sound like overwhelming negativity.
The _____ in the box was just another clunky plot device that ultimately went nowhere, just like the bird. It was as though the screenwriter randomly threw in stuff but didn't know how to (or didn't care enough to) integrate it into the plot and to create resolution.
No, it was integral to the plot as it served as a trigger for Kelly to relapse back into drinking. Of course it also showed that there was a lot of hostility towards her (in addition to loyal fans showed by sold out concerts) and anything and everything could serve as a trigger.