Nice summary and some good arguments. I really appreciate a lengthy write-up and a conclusion that tries to draw from a larger picture of the discussion up to this point. 
Some meta comments about this topic
Consuming a long forum topic like this one is cumbersome and often falls into a feedback-loop of people petitioning for their position instead of contributing new or meaningful discussion. I think organizing the discussion is important to avoid this topic becoming a mega-topic.
I’d like to encourage anyone who skimmed through this topic and gets an urge to petition for or against this feature, please don’t “make more noise” for the sake of noise 
Has this topic become a mega-topic? Is it worth summarizing the major points (and pro/cons) and then closing to help the discussion progress? In order to keep the meta-discussion away from this topic, feel free to reply to this specific post here instead: Please close the mega topics (ternary and companion objects)