I think your points are a bit too negative. If I had to phrase it I would say...
Monogamy is based on stability, safety and less change, and a journey taken together. Polyamory is more about each person's individual journey, each on their own. It is more expected in monogamy that big events in your life will be shared, while in polyamory, you can have big events in one partner's life (marriage, pregnancy) that don't affect you directly (even though they can affect you indirectly. It's not YOUR marriage or YOUR biological child, though).
In monogamy, there is that feeing that anything you do is more likely to be shared by some kind of osmosis, while polyamory is a more complex beast and things do have an effect on you but you're not always sharing the spotlight anymore.