People are practicing and preparing for boarding groups. 61 boarding groups going within a minute is anticipated to represent around 6,100 people already in the park and being online securing initial Boarding Groups. The remainder of the people represent thousands more who secure backup boarding groups.
Basically, RoR is popular and people are doing what they need to to secure a BG. I personally can't see this changing to FP anytime soon as I can only imagine what kind of demand that would put of their servers each day when anyone who wants to can try to get a FP for a future date.
I think for now, BGs are their best option and hopefully here to stay for a while. I'll take this over waiting in line for hours for FoP, any day!