Interesting. I think I agree that my group doesn't tend to explore the world for its own sake, and that PCs go about pursuing their own goals.
Nevertheless, we do at least sketch out the world, or at least the parts of it that seem likely to be relevant. Part of that is that my group genuinely enjoys worldbuilding. (For us, it isn't a solo activity of the GM.) But also because that sketch tends to inform play.
If I don't know what the neighboring lands to the starting area are like and what their relationships are, I can't create character goals involving them. And if they're created on the fly as we visit new areas, we're likely to introduce inconsistencies and I'd guess things would feel a lot less organic. Not that any of that has to matter to you or your group, of course.