One of the major change introduced in BI Apps 11.1.1.7.1 is the way how we manage the ETL task sequence and trim the unnecessary tasks.
This functionality was accomplished earlier using DAC. The problem we frequently faced was that the DAC repository and the INFA repository are maintained as two separate repositories. We have to sync up the name of tasks exactly in order to use DAC to manage the task execution of the Informatica workflow tasks.
Load Plan and Load Plan Generator was designed for addressing this requirement.
Here is a good article that describes the story.