Hmm, interesting perspective. So there is actually something deeper (on top of other already deep stuff) in having, and more importantly raising kids.
Since they take away so much freedom (if they don't one ain't doing parenting right, thats for sure... or simply doesn't have to work at all), its the little bits of passion that are hard won that I appreciate so much. They very effectively throttle any non-kid activity, 24/7. That weekly climbing evening with a buddy is a highlight of any week it happens. That rare hike or skitour that I manage to pull off during weekend becomes a very fond memory. Those 2 weeks spent solo backpacking in Indonesia or recently Dominican republic is something etched deep in my soul.
Before kids, I did all this every weekend, remote trips 4x a year. I was in heaven, but it became the new, even if ultra cool, norm. Now with kids, and after pretty bad paragliding accident that left me on wheelchair for a bit, anything I can still do, I want to dance with joy. I know intimately how it feels losing all that, maybe forever.
One thing that can break this circle IMHO - passions. Climbing is one for me, nature/mountains are generally another. I can keep doing climbing all the time, novelty doesn't wear off. Maybe it can again become a new norm, but what a norm it would be. But maybe that's just idea of a dad with 2 small kids and way more dreams than life can still deliver. Maybe that slow dripping makes it actually better, I'll never know.