petitioning for the complete dissolution of the cship would take many years & would most likely not work out in Britney's favor right away. that's a very long process. if that petition was eventually denied, her father would still be in charge & she'd just be right back where she started. her priority right now is having her father removed, which has only recently seen progress.
once Jamie is removed completely, she may begin to petition the whole thing down the line. but right now it seems like they're taking the "baby step" route to make sure she is successful in finally having him removed. that seems to be the most pressing issue for her at this time.
in my opinion, the whole freedom movement is in regards to her freedom in general. whether it be from her dad or the cship completely. we are supporting what Britney wants in terms of her freedom.