Probably because she doesn't want it to overshadow Roar and wants to give everyone a chance by not owning iTunes Top2.
Remember she's the one saving Epic Records, ha humanitarianism >>>
Saving record labels, bringing multiple artists to the mainstream (Juicy J, Snoop Dogg, Kanye West), de-throneing Blurred Lines on iTunes (and soon to be the Hot 100)... she may be as close to Jesus as we ever see in human form.