Improved health for people not living that way.
More freedom to live as you choose. Heteronormative culture has long pressured young people to get married and have kids and told them from birth they are straight without giving them time to figure out for themselves what their sexual orientation is.
Freedom to leave a marriage that isn't working because you no longer are a prisoner of the fact that your wife knows all your health issues and the dietary restrictions they dictate and cooks better than you, so she is essentially irreplaceable because that catalog of data about you isn't readily replaced by merely marrying a good cook -- assuming you can even arrange to remarry immediately and aren't forced to feed yourself (inadequately) for months or years while looking for a wife
Fewer mental health issues from society no longer dictating to everyone "You will be straight, don't confuse us with the facts. You will fall in love with The One meant for you, never mind the overwhelming evidence this is the exception not the rule. You will fit your entire life around tasks society decided are yours at birth due to the bits between your legs."
Less homophobia, less transphobia, less misogyny, more economic stability due to more personal flexibility.
I don't even know what you're talking about with this 'Freedom to leave a marriage' part. It seems like a smorgasbord of ideas smashed together rather incoherently, my apologies but it's after lunch and maybe my brain isn't all functioning 100%.
Ok I also don't understand what you're talking about in 'Fewer mental health isues' either. It seems like you're trying really hard to imagine a fantasy reality where non-heterosexual people can live by themselves - but with a partner if they want - but they can leave - but they should be able to leave and be by themselves and be just fine - all with regard to COOKING specifically. Am I getting in the ball park there? I don't really know what you're getting at. When you deviate from 'normal' culture, life is going to be harder for you. That's how our world works. The people that have and are trying to change that... just watch for if things are getting better in their wake, or worse in their wake.
I suspect economic stability comes more from personal responsibility than 'personal flexibility'. One must make great sacrifices, in general, to develop the character to be able to progress in most areas. What I typically see from the crowd wanting more freedoms is the freedom to be more hedonistic, where I see the people more grateful to exist and actually progressing growing their discipline and losing their selfishness.
>>> "in crisis due to various social factors making full-time wives and moms relatively rare"
>>> "It seems likely to me we need to rethink and rework our food culture so everyone can eat adequately"
How could the second work without fixing the first?
I've thought a lot about this problem space and the connections I have listed are clear in my mind. If it's not clear to you and you are interested in the idea, you are welcome to do your own reading and thinking and draw your own conclusions.
Given that I met exactly one woman with children who didn't feel affronted by how I was living, I imagine my opinions and such fall far outside the Overton window -- which seems to be the story of my life.