I think that the majority of poly people still want the "normal" things like marriage, kids, that whole home life etc. Many poly people had those things before they started having open relationships to begin with. Everyone I have ever dated sees that sort of thing in their future, they just don't want the monogamy part that is often associated with that type of relationship.
What I was talking about in the examples I gave was the fact that is my partner (who I have decided not to split with despite these issues) has a "toxic spouse" that he lives with, I can enforce boundaries about the physical space we share. I can decide that I never want to be in her vicinity, or somewhere that she could potentially be, that would include her house. That would affect my relationship with my partner because his house would always be off limits as a location we can spend time together. I am not talking about us potentially living together, simply because I can't see that relationship style in my future. However, if he did have a toxic spouse, that would mean that option was forbidden, rather than unlikely. I don't particularly like relationships where things are forbidden. I much prefer things to be unlikely because of compatibility issues rather than because someone else doesn't want that to happen.
I, too, am not keen on fostering close metamour bonds. However, I don't want things to be so bad that we could never share a physical space in order to accompany, support or spend time with our paramour. That takes effort from all of us