I question if this is really a top priority.
I do agree that being a premade team and on voice does improve the overall team strength quite a lot. But then it also seems to me like it's always the same people that play together (at least in my 1600-1800ish rating bracket), thus their rating naturally represents them being pre-made already. I have found this to be no issue for me in TMM.
A factor that I think causes way more problems to the quality of games is a premade team with a very large rank disparity. Like 2200+600 queuing together, and getting matched against a pair of 1400s. These games I always find very non-enjoyable, and the outcome is also very volatile depending on the size of map. On big maps, the even-ranked team has basically no chance, as the higher rated player has time to take some of the lower rated player's resources and outscale. On smaller maps, the team with the large rating disparity still has a very large advantage if on voice, as in my experience the coaching/help on major strategy calls from the better player can make a large difference.
