Currently the LB (L1) & RB (R1) buttons are unused in menus, so my Idea was to give the a use case.

Let us use them to switch between Tabs in the Quick Menu and the Main Menu. So that pressing RB (R1) would switch to the next Tab to the right (e.g. Launch Pad to Notifications in the QM or Worlds to Avatars in the MM) and LB (L1) would switch to the next Tab to the Left (Camera to Here in the QM or Social to Avatars in the MM)

This would be really cool addition and would make it more similar to how other games handle controller input.