I’d suspect there’s a high correlation with better birth control options.
In the 90s, women had to be diligent to take a pill every day. Hell, I can’t even be trusted to take a pain pill when I have a headache.
I can’t tell you how many times an SO and I had a scare because she forgot to take a pill for a few days. I think this is doubly so when you’re in your late teens/early 20s and still don’t have a good understanding of risk.
Now, women can get an injection that lasts 3-6 months, or an implant that works for years.
So we’ve lowered our risk significantly and now it’s more skewed towards family planning. I think that’s a great thing - let the people who want to have kids have them, let the rest live out their lives how they envision it.
But family planning is tough and there are important factors that others have mentioned in their comments here. Money, opportunity, timing, support. I didn’t start having kids until my 40s, but if things had lined up better, I certainly would have preferred to be a Dad a little sooner.