I agree "Goodbye Love" was needed to show the relationships between Benny, Mimi, and Rodger, and also to explain a bit of Rodgers fear of watching another love "Die", and his own fears, so he runs...
I think Halloween was needed because it ties up how everything has come together to that point, and explain a bit, why at that point, everything between them all, has gone to hell.
I'm not sure why he removed all the breaking up and getting back together of Maureen and JoAnne (over and over again). The volitility and passion of that relationship is what drove it. (I hear it was due to 'Politically correct' reasons of waning to show the 'gay' relationship in a more positive light)
Also the Character of MiMi was too serious. they took away her "Ditzyness" she wasnt as cute and playful, but more streetwise and serious. (Maybe a choice by the actress?)