I disagree and I've probably traveled to some further out places than the average South East Asia/Australia gap year person...
You get a better sense of the 'big picture' by reading decent news sources - economist subscription and frequent visits to the bloomberg website will do a lot more for you than 'traveling'.
Traveling is fun, introduces you to people you might not otherwise have encountered and gives you a low level up close look at other countries. It doesn't however give you some vast broad worldly knowledge that other non travelers can't acquire - that's quite frankly BS and will just make you sound like another numpty who 'worked all summer' to fund (about 10%) of the same generic gap year mummy and daddy paid for prior to uni.
Visiting a big rock in Aus, going fruit picking and firing an AK47 at some chickens in Cambodia are not going to do a great deal in terms of your general ability to have an opinion on matters or comment on world events.
I agree and disagree to an extent.
Firstly travelling 100 years ago, and even 50 years ago would have quite possibly made you more worldly about different cultures, however now we have the internet, newpapers and tv news that tells us stuff before as it happens. With the number of cultural programs on TV you don't necessarily need to go to the other side of the world to start to understand the culture, however it helps...
It all depends what you do and how you act when you're there, if you go with a closed mind and spend your time in a luxuary hotel drinking then you may as well have stayed at home and read the paper/watched tv culturally speaking, however if you get off the beaten track and actually spend time with people from that area/country and keep an open mind then you may well gain something that those that haven't travelled will not.
The problem is most peoples idea of travelling is either a package holiday (and lets be honest we all go on them because the are convenient and inexpensive and sometimes useful at insulating us from the actual culture of the area we are visiting, sometimes we just want to relax and not have to think about the hardship outside the hotel...) or doing the south east asia tourist route, like the thousands of other 20 somethings every year, most of who spend their time ****** and socialising with their fellow countryfolk. Obviously both of these will give you an understanding of the culture and nitty gritty of the area you are in but it's more the tourist culture and not the real culture (A bit like going to the major london tourist attractions and thinking that is how everyone in England lives).
I guess to get the "real" culture and get under the skin of the area you need to spend a significant amount of time in the country, with the locals, which is very rare in reality. However good reporting could quite easily give the newspaper reader at home just as much understanding...
What I think "travelling" does instill in people who do it is a much broader sympathy as such for other cultures and they way they do things, especially things that people in the UK may consider barbaric. Just look in loads of threads in here where something that is different to what would happen in the UK is classed as barbaric, whereas those exact things in the middle east for example are perfectly fine, whereas sex before marriage..!