I highly doubt that there would consistently be 12 people (3 groups of 4) queuing in the group queue to enable reasonable wait times. And even if there are 3 full groups queuing regularly, it would get boring fighting the same group game after game. Even then, one or two of those groups would likely be significantly worse than the other(s). I would expect the less powerful group(s) to stop queuing due to being beaten over and over.
Unless I'm wildly underestimating the number of people who want to just do 4 man Premade v 4 man Premade v 4 man Premade, a truly functional group-only queue seems like wishful thinking.
ZOS could create a whole new incentive structure to draw more players to the Group Queue in the hopes of getting it to function. Or they could allow duos and trios in the group queue and draw from the solo queue to fill in the gaps in some complicated fashion. But in reality, we can't hope for any change that requires significant time and work from ZOS.
Simply allowing solos and duos, instead of solos only, seems like the easiest way to appease the folks who are rightfully upset that they can't BG with friends. It can't be that hard to increase the permissible group size by one. ZOS wouldn't even have to balance the duo by modifying how matchmaking factors in the duo's MMR. The team with a duo may have an advantage, but so what? It won't be insurmountable.
Adding duos to the solo queue is an easy change that lets folks play with a friend, while still preventing unstoppable premades from hindering other players' enjoyment. Adding a group-only queue isn't a feasible solution. Change my mind.
“There is nothing either good or bad, but thinking makes it so.”