Born and raised in the heart of Miami... the arguments that there is "more to do" in Miami and that is the reason why the stadium attendance continues to be crappy is just a giant load of horse manure. Miami fans are awful fans, I'm not referring to people on this board, but the south florida fan base as a whole just doesn't know how to be a dedicated fan.
JCANE can attest to this.... even the mighty University of Miami was struggling to fill up the Orange Bowl before they moved to SunLife (where it is basically impossible for them to fill up now). Up until a few years ago there were a few certain things.... death, taxes, and the Orange Bowl stuffed on saturdays. but once the product started to take a step down, the "die hard university of miami fans" stoppped going to the games.
Heat games? My family became season ticket holders in '89, 2nd year of the franchise.. ive watched the demographics of the fans change with the influx of South American's, especially Colombians, who have moved to south florida and brought their culture (and money), good and bad with them.(have nothing against them, ex girlfriend was Colombian so i got the full on experience). In Colombian culture, showing up on time just isn't important and isn't disrespectful. the majority of Miami Heat season ticket holders now are South Americans, and when you watch games and either see empty seats midway through the 1st quarter or empty by the middle of the 4th, its because they just don't see anything wrong with showing up late or leaving early.
Marlins... does anything really need to be said? Steal money from the city, build a palace for them on sacred OB ground, and they still cant give away tickets for people to show up midway through the season.
The bottom line is the nature of the Miami Fan has become to show up when the going is good, and jump out when its not. The easiest way to bring back the fans that will fill out the rest of the stadium is to win football games consistently.
A great sports town can survive not winning and keep fans in the stands.. Miami is not a great sports town, doesn't have great fans, and doesn't have a winning product.... is it really any big surprise that seats are consistently empty?