Beyonce does not need to perform all of her singles at the VMAs, especially when the general public doesn't like one of them. BTINH doesn't even fit the show's demographic and will have likely peaked by then, so that would be a waste of promotion. End of Time is the next single, and the VMAs is the best American promotion it can get. 4 needs a smash hit in order for it to continue selling well in future weeks, and EOT is that song. It makes no sense to keep pushing things that aren't going to get any better. Beyonce should give one amazing performance of one extremely successful song than give a medley of a flop, a moderate success, and a potential success.
the vmas need to get ready for 
