I'm not missing Fed or Rafa either, but apparently ticket sales have been affected:
@BenRothenberg: Attendance for Miami WAY down this year, probably due to weaker field. Often falling short of previous attendance highs by thousands. #SOT13
It's a shame - if I lived in Miami, I'd love to go to the tournament, with or without Rafa or Fed. I bet the tournament organisers are dreading the day they retire, they must bring in so much ticket revenue wherever they play.