you've given them a penalty for having kids
Nonsense. I've subsidised their lifestyle choice and the market has accurately rewarded their work based on their experience and hours.
Women can choose not to take time off to have children. I know some that have made that choice. I have no issue with others that prefer a different life, as long as they accept that there are trade-offs involved.
A thought experiment - take a married couple, put them in the same job. If they wish to have kids, the woman will suffer at least some lost time. You can argue that the man should take some of the hit on parental leave, but that doesn't change the fact that regardless of both the man and woman choosing to have a kid, only the woman is guaranteed to take a penalty to her "hours" and "experience".
This may be a cultural difference, though - Canada provides paid parental leave, so the perception may be different here. Or maybe when men take leave (I took three and a half months the year my kid was born) it doesn't get counted as a gap in hours or experience. At least, there's never been an instance where it's come up.