I tend to think that both extremes are foolish and the correct answer is that we can't draw much useful information from knowing that a person has children when it comes to deciding how society will unfold.
I have an eight year old kid and although I am a very different sort of person now then I was back before I had a kid I can't say that doing so made me a better governor. I now know how I react when pushed to my emotional breaking point, what it is like to deal with extreme sleep deprivation, and how greater conflict with my spouse feels. I have felt protective towards Elli, but I certainly haven't felt the extremes of irrational overprotectiveness that parents are so often portrayed as feeling. People seem to take that sense of desperate worry as a sign of good parenting and see valuing my own offspring above all other things as a virtue. I don't see it that way, and certainly haven't had my feelings go that way. Elli is important to me but not in the way most people's kids seem to be important to them.
All the time I spent taking care of Elli could have been spent learning other lessons. I could have taken courses on history, learned about social work, volunteered, or read more about politics in that time I invested in her. I am pretty sure those sorts of things would have given me a better understanding about how to make policy then playing peekaboo ever would.
Being a bit nuts about your kids is, it seems, the default state for parents. I have seen plenty of people stand around agreeing that helicopter parenting is a problem and wish for the good ole days where kids could just play... and then admit that their kid has nearly every hour from dawn to dusk booked solid with activities, weekdays and weekends alike. They know that the activity treadmill isn't good for kids, they don't like it, and yet they can't get away from feeling like their particular kid needs ALL THE THINGS or they will somehow fall behind. They want the absolute best for their children no matter how much it makes things worse.
But I don't think that this tendency really matters much when making policy. People tend to want things that will protect their interests and the interests of people like them regardless of whether or not they have children. In any case most parents I know are desperately focused on getting past the next day or week, just trying to keep their heads above water. They aren't going to be overprotective of the future because they can barely figure out how to have time to look at the future at all. Maybe they start sacrificing the present to deal with the future after the kids move out and things quiet down, but generally I don't think you can count on parents to spend their time figuring out what will be the best for everyone twenty or fifty years from now.
Basically decisions should be made by those who are best informed and who recognize both that preparing for the future is important and that because we know so little about how the future will look we can't place too much faith in our models. A model of the future from 1990 would essentially ignore the internet of today and that makes the model pretty much useless. We should think about the consequences of our actions while acknowledging that our certainty drops off drastically once we go more than a few years out.
Whether or not you have squeezed out a couple of rugrats in your past has little to do with your ability to do these things. Have children or don't, but the idea of placing people who chose differently as being unfit to make policy decisions is hubris and nothing else.