From Fedora Project Wiki

I'd like to suggest retaining LVM as a default (with btrfs atop), with perhaps an easy one-click anaconda option to switch out the default for btrfs-only. After all, there are already a bunch of storage selection dialogs, so this would be easy to achieve. The benefit to retaining LVM by default is flexibility - ability to assign volumes to guest machines, move volumes that are not btrfs around, resize swap, handle encrypted data more easily, and so forth. A wholesale replacement with btrfs for volume management would loose a lot of functionality. --jcm