Doesn't really say why, or does it? I am not a big traveler, so I am probably wrong, but in a way, traveling seems kind of passive to me. Sure, you get to see lots of things, but seeing (and learning) is passive. How am I going to change the world doing that? I would need some kind of spin to it, like at least being a successful travel writer or something. Otherwise, what are the USEFUL experiences to make? Would be…
It seems hyperbolic, but go to any practically and hostel in a developed city worldwide and you'll find a group of Americans doing just that (not to mention other debaucheries).
Traveling actively is basically the exact opposite of that. It takes research, bravery, spontaneity, social skill, and a boat load of curiosity. When you travel like this though you can paint yourself into entirely new environments and see the ways you expand, you can look back into the ways you live normally and then pick and choose the parts you like the most. In this way you can actively change your own world and certainly put yourself in a better place to continue making positive changes.
Most immediately: you'll soften your bias and become aware of the biases of others, you'll understand the traditions of your culture and be better able to interpret their necessity or value, you'll become experienced in some other culture able to interpret things through a slightly different point of view. Together these things can be used to vastly improve your home or can become skills to help you change the world.
Of course, if you want to travel and at that very moment do some active changing, you may want to try something like Peace Corps, Doctors/Engineers Without Borders, or other world health initiatives. You should be careful though because if you don't have the experience which can let you isolate your own cultural biases a little then you may get connected with some group which will inhibit your ability to learn. In my opinion, this is the trap which things like mission trips fall into and, as an effect, they may become some kind of mixture of harm and benefit.