Projecting payroll and average annual value (AAV) is important as the two are both functions of population size and density, team quality, team enthusiasm, unemployment, consumer wages, and consumer confidence, among other factors.
While the AAV is used for luxury tax calculations, and teams receive fines and penalties for exceeding the luxury tax threshold (which is $206 million this year), the actual figure is incredibly important as it represents how much money is spent on the roster each year. It is important to remember that major league baseball is a business first, and businesses lose money if they incur more costs than they generate in revenue.