The new ending doesn't work because it is not supportable by what came before it in the movie. In a Q&A with the screenwriters (Creative Screen Writing Podcast, highly recommended), one of the writers discussed how the scene that set up the new ending was cut. As it is presented in the movie it would not led to peace as described but rather an escalation of conflict. He is hoping to see it in the director's cut since it was in every rough cut of the movie but the final print.

Rob