When people start with SAFe there is a lot of confusion around the need to assign a Business Value to the PI Objective. The thinking goes “we already understand the business value because we have the features - why not just use that?” In many ways this is the same kind of thinking process as “why do we establish sprint goals when we have users stories?” The problem with this type of thinking is that if you are not careful features and stories become a way of specifying fixed scope, do not allow learning as we go along, and set us up for blame game when things don't quite work out as expected (Business: “But the features says it has to do this!”; Team: “We thought it meant that and this is how we got there.”) To rectify this, we treat the features or story as a “wish” and the PI Objectives (and sprint goals) become a feedback loop to that the team provides to ensure there is common understanding. (See What is the Purpose of Sprint or Iteration Goals? for more information)
Having established the PI Objectives, we need to close the loop on communication, and we do this by having the business owner review the PI Objective, discuss their understanding of the PI Objective with the team, and assign a Business Value to that PI Objective based on that understanding. This process creates a “handshake” between the business and the team, with the PI Objectives in the team’s own words and the Business Value is the agreement from the business that the Plan makes sense to them.
In addition to closing this loop, there are two other primary uses of the Business Value that is assigned to the PI Objectives:
In summary, “Why do we assign a Business Value?” To enable local decision making and to understand whether we are making and meeting commitments.