You don't have to set the meta in stone to have a role queuing system, separate it into two queues.

1 - Queue for freeform meta meaning the team won't follow the conventional meta
2 - Queue for meta, 1 Bruiser Top, 1 AP mid, 1 Jungle, 1 Adc and 1 Support

I expect almost everyone will choose option two but at least this way they can improve the game without solidifying the meta.

I think this is a terrible idea because people will actually get to play the role they want to play. I hate it when people get what they want.