Exploration works best when the journey is more important than the destination. Which is not what modern D&D adventure design does.
Very good point.
I also think that I have personal reasons for exploration being potentially my favourite pillar: real-life experiences.
When we were kids in the 80s, exploration was one of our primary ways of having fun. Not on a daily basis for sure, but damn often we got ourselves around exploring unknown and (especially) forbidden places. We lived on the outskirts of a city, on one side of our neighborhood we had the countryside. Not a very wild kind of countryside unfortunately (no forests where I lived), but we still did things like going into farm fields to steal corn cobs, rally-biking in mining sites, infiltrating abandoned factories and even a giant villa... But the other side of the neighborhood was just as good! There were underground garages, warehouses, once summer we even infiltrated a skyscraper under construction and went up to the helicopter port on top of it! One of my friends who had already been up there a few days before, and knew there was a lowered (and safe) platform all around the heliport but being a meter lower it was invisible from just a few meters away, went close to the edge and pretended to slip and fall over, only to land harmlessly just below. The s.o.a.b nearly had me a heart attack! Last but not least, there was a huge apartment complex in our neighborhood with interconnected cellars basements, which we used to call (wait for it...) the "dungeon"! You could really get lost in it
Certainly most of the things we did were safe, but we liked believing we were brave. Others probably could have killed us (entering constructions sites...
not recommended!) and we didn't even realize. But... combat? Fighting? Physical confrontation?
No way! It did happen on very rare circumstances but nobody wanted to be part of it, much less look for it, we would all run!
Looking at the kind of media entertainment today, TV/movies and videogames, I can imagine that people are used to the idea that combat is the main deal. There are of course also exploration-based games, but the majority I see have fighting as the main theme. But I grew up with Lucasfilm and Sierra point-and-click adventures and I cannot erase that part of my education!

Even in my short stint at World of Warcraft I ended up avoiding monsters and just looking around in weird places
