Why yes, Jack . . . I practically know everything about tennis.
Totally, kidding . . . The tournament officially began in 1974 and had several different names and sponsors including American Airlines Tennis Games, the Congoleum Classic, The Grand Marnier/ATP Tennis Games, The Pilot Pen Classic and the Newsweek Champions Cup.
The women's event was always held the week previous to the men's event and had sponsorship titles like Virginia Slims of Indian Wells, the Evert Cup and the State Farm Evert Cup.
It was in 1996 that both tours collided into the format we see today. There are 96 players in each draw; not 128 because the top 32 seeds get a Bye in the First Round.
The increase in the size and scope of the tournament was largely due to increase its status from obscure desert tournament to a blockbuster event just below the four major Grand Slam tournaments.
The tournament in Miami is similar in its philosophy to grow to be a step-sister event to the Slams. I think they both work because it is a great way to move the tours out of the winter tournaments into the thick of the tour and major tournament calenders.
I hope this helped.
ATPWorldTour.com and WTATour.com