I was talking about this with DH recently and he agreed with much of what I said.
It strikes me that boys and men have very "optional" lives in comparison to girls and women and that this influences their whole approach to life. What I mean is, girls learn pretty early on that their choices will be restricted, that their options will be limited. From only being allowed to wear skirts and then told they mustn't show their knickers (thus removing the option to be active) to suddenly having to deal with periods and curtailing activities due to that, to then contending with the prospect of unwanted pregnancy and thus having restrictions on sexuality to then being told not to walk certain places not to do certain things for fear of being attacked and ultimately being told you "can't have it all" - ie choose work or children.
IMO, women (in general of course, not all) learn very quickly that there are consequences to things, that you can't always have what you want, that sometimes you just have to get on with it and face the fact that everything isn't perfect. I think that influences their approach to so many things in life from housework, to illness, to childrearing. Men on the other hand, always seem to have options open to them and I think that leads to a certain immaturity, a lack of acceptance that sometimes you can't have what you want. I think it has a bearing on how men approach things like fatherhood and the idea that now you don't have any choice but to knuckle down and accept your life is different - so many men seem to want to "opt out" and carry on as if nothing is different, thus leaving women to, as usual, take the hard road.
While I don't think it's right that women often end up carrying the burden I'm not sure it's necessarily a bad thing to have that maturity foisted on you. I think while women do lose out massively in the earlier years, especially when children are young, that maturity and that acceptance stands them in very good stead as they get older and ultimately they reap the rewards. I notice among older friends that women seem to come into their own in their 50s whereas men can't face that their options are now becoming limited and they no longer have the world open to them - hence mid-life crises etc. I think also because men expect options they tend to skirt on the edges of responsibility, never full accepting the hardship of, for example, parenthood, and thus ending up on the fringes as children get older and become true friends and companions. Thus women, who have been the stable guiding force in childhood, mucking in, organising, being the go-to person, reap the rewards of a close relationship with their adult children, whereas men, who focused on work, never really got their hands dirty with parenting, are now coming to retirement and the loss of that source of status but have not really jumped in with both feet in family life and so don't have that either. They are left with very little.
I am not saying the equality that exists is a good thing. What I'm saying I suppose is that while women look on enviously at men continuing their careers and never attending a parents' evening, they might do well to remember that the emotional toil and labour they put into their families is really and truly worth something. Jobs come and go, they give no love or longterm support. But children are for life, and being that person who always knows where the PE kit is is important, is special.
Men are missing out. They just don't realise that until it's too late.