They don't want people dropping out of the match to join a fp. I support their decision to do this, queue for one or the other.
Sure if you can pop an fp as quickly as a wz. As it is I can go through 5+ wzs without group finder finding an fp group and that is with 4 of those WZs being full timed Huttball matches. More people rage quit from WZs because no one is organizing. Better to get ingame vox than force people to sit with the game minimized waiting for an hour plus in the hopes the group finder sound fires to announce they can finally play an op.
As I stated originally before creating a negative find a positive. Don't remove ability to remain queued for an FP unless you add something positive to replace this feature.