From talking with those familar, and having observed the wait time data when FFN was active--the event seemed to be lower than expected for guest appeal; and in the process, led to reduced crowds with most of the waits hovering in the 30's for the event as a whole.
It's why they cut Pets from the attraction list this year, as a result of that matter.
I suspect that with the expected size of crowds, USH might be willing to use FFN as a test subject for the weeks the event operates ahead of Memorial Day, when that will have escalated crowds as a result of the holiday. I can be wrong in my logic, but I suspect getting things stable by testing and gauging how it works for FFN will make more sense than doing it on "Normal Days".