At 40, to be honest, they're probably in the thick of parenting themselves: looking after teens and quite possibly with elderly care kicking in. So I'm not surprised their conversation isn't immediately all about how much they're looking forward to caring for grandchildren! 
Seriously WOMEN STILL DO THE BULK OF CARING - AND IT'S NOT FAIR!!! And it is quite likely that this is a situation IMPOSSIBLE to sustain, given that women are also wage-earners. Society needs to do something.
On another level: You'll always get a fraction of people like this. And you see it sometimes on the responses to an OP on MN. A woman posting because she's struggling is going to get a few responses along the lines of: "Well, I had a tough time, suck it up."
The majority of responses, though, will be positive, sympathetic and supportive.
As on MN, so in life. In most RL cases, women will go out of their way to try and improve life for their children - and for other women, generally: thus are political movements born, with no hope of realisation in the present, but hope of long-term achievement of goals.
I'm guessing a lot of the men in your office were oblivious to the whole conversation, though? 
Anyway, just be glad you're not the offspring.
And, you know what, there is also the fact that an awful lot of people are massively emotionally literate and/or emotionally articulate. Perhaps they're on a journey themselves. Stage 1: acknowledging how hard parenting-as-a-woman is (not an easy stage, there is a lot of propaganda and ideology that keeps women feeling along, guilty and silent about how hard it is). Stage 2: Expressing and being able to share that acknowledgement about how hard it is. Stage 3: feeling angry, rather than depressed and silent.
Stage 4, ideally, is about finding an action that draws on this experience and improves things. This takes time. It requires, apart from anything else, finding an appropriate object for the anger, and being able to formulate future goals and possible actions.
Obviously, they;re struggling a bit with Stage 4. At the moment, the anger is directed against women they perceive as having evaded the power imbalance of gendered parenting, and their action is to withhold labour that they experience (without fully articulating this) as having being unequally coerced from them.
I suspect that it might take acquaintance with an experience-based discourse - such as feminism - which has been developed elsewhere to turn their current Stage 4 into something more positive.
But it takes time to develop and/or find an alternative discourse. It's not an idea that is routinely put forward in media 'think-pieces' or in popular culture. So you have to search it out, and take time and effort searching it out. All of which can be in short supply if you are working in and out of the home, parenting, holding down a wage-paying job, etc.