Wisdom in one context can be foolishness in another. To live a good life it is necessary to re-evaluate the actions of your forebears and determine if it is still applicable to your modern context. That doesn't make someone a "social iconoclast", it makes them wise. Our ancestors did the same thing to their ancestors. Homo sapiens is 300,000 years old, and our societies have changed a lot since then, and will continue to change.
Note that I personally have no desire to be anything other than monogamous, but I know several people (both young and elderly) who are successfully polyamorous. I also know people who have catastrophically failed at polyamory; but then, of course, I also know people who have catastrophically failed at monogamy.
As far as I'm concerned, normalizing polyamory will strengthen monogamy. It seems like some people out there just aren't cut out for monogamy, and in a monogamous world they inevitably become cheaters. Let the polyamorous people remove themselves from the monogamous dating pool and you will exclusively remove people who would otherwise be compelled to cheat.