Here is my take on that. If there was horrible weather then of course you want to be protected because you are giving a show to the people at home. The people in the stadium are more concerned with getting something to eat or going to the bathroom. You want it to be perfect for television. So, you pre-record everything and if something goes wrong you can use that track but if everything is going well then just let the people play. Let there be some spontaneity. I feel like the Super Bowl halftime show is turning into an episode of Solid Gold. Google it sometime but it was a show that featured "performances" from bands and singers that sounded remarkably like their records without any of the instruments or singers being plugged in. In the background a bunch of dancers who were castoffs from Flashdance shimmied in the background.
I have seen the Red Hot Chili Peppers play in arenas, clubs and huge stadiums. They never had an issue bringing it. They are not Britney Spears. They really don't need help. They know what they are doing and sometimes the NFL should just let the people who know what they are doing let them do it.