During my marriage to my ex I was at times either part time, or a SAHM. We agreed on this together, with the plan being that I would take on the lions share of the housework, and childcare, to facilitate his career progression. Then, once DD1 started school (so childcare was cheaper) I would start up working fulltime again, and exH would take on more of the household and child care duties and ease off on his career for a bit. The end goal being that we would both be earning well, and hopefully have a bit more flexibility.
When the time came, he didn't want to even pick up his share of chores. Our relationship suffered, he became very controlling and eventually abusive, so we divorced. At this point, his earning potential was about 3-4 times what mine was.
I was very lucky in that, we had enough capital to allow me to have a greater share, to set me up with a mortgaged home, with payments I could afford alongside childcare and bills. If that hadn't been the case, we would have looked at maintainence.
His higher earnings weren't just earnt by him. If I hadn't supported him every step of the way, he would not have been able to progress to where he was. He would not earn what he does. He would not have had the pension he has. And I had to start pretty much from scratch. If we hadn't been able to negotiate a clean break from share of assets, do you really think it would have been fair for me to just walk away with next to nothing?
I think these things have to be looked at on a case by case basis. If one partner has contributed very little, then beyond ensuring the DC are adequately housed and cared for in both homes, then they probably don't deserve much. But if both partners have worked as a team to build their lives and livelihood together, then a large discrepancy needs to be taken into consideration.