There is still something extremely valuable to be found in visiting all of these places. Indeed, the more time he spent in each place, the more he would learn--but there is a limited amount of time and the world is huge. You could equally argue that he should have visited and/or lived in every town, since every town has its own unique experience.

By your standards, what does "living" somewhere even consist of? Staying there for a month? A year? 10 years? I've been places for a year and don't feel like I "live" there, and I don't see how arguing that he should have "lived" in 193 places is a valid criticism. Nor is asserting that he's only traveling for the stamp--he refers often to what he's learned about people and the human condition, and the stamp is simply a proxy for measuring his progress in this journey, since you really can't measure "how much have I learned while traveling?" until way after, as he says.

While it's not strictly necessary to visit every single country, I think what he's down is incredibly valuable and that people should travel even more for better cultural understanding.