In my eyes ranked is only for the most common games. For niche game modes you still have the lobby to play such games. At least that is my opinion about ranked games. For me 2v2v2v2 and FFA are both niche settings. Feel free to disagree with that opinion.
Some days ago there was a suggestion to Sudden Death to the ranked mode. This was my response:
It was kind of the same as for these game modes. I do think both 2v2v2v2 and FFA can be part of the brawl mode for some time.