Oh cash is absolutely part of the decision. It had to be part of the discussion they had when deciding on if they wanted to add just one race or two. They've said as such when they gave their explanation; they had to balance out their want to add something for the fans (viera), adding a beast race (which was something other MMO's have and FF was lacking), and deciding that their staffing levels would only allow for designing 1 male and 1 female options. They're all business decisions, including considering what would be the most enjoyable for the player base at large.
Money is always part of the discussion for business, but I think they made their decision based on the logistics of the situation and a broader look at what they wanted in the game rather then "bunny girls will move those fantasia sales! Get to it!"