Visa Time
I don't get the point of certain countries making people from ONLY certain other countries get visas. I'm sure someone with a better background in national security can explain it to me, and I'd appreciate the education. But in a nutshell, if you're a country that relies heavily on tourism for a good portion of your GDP and a lot of people want to come spend money there, common sense says you'd make it a little easier for people to do it. Of the 5 countries I'll visit in the next 7 weeks, two (Vietnam and Myanmar) required me to obtain a visa (or application for a visa) in advance.
It was a time-consuming pain in the ass. And that's coming from a New Yorker, who can be at any foreign embassy in about ten minutes. The cost (about $50 each for Vietnam and Myanmar) isn't a ton when you compare it to New York prices and rationalize that's only about 2 cocktails on a Friday night. But it is considerable when you compare it to how cheap it is to travel to those countries. $50 in Vietnam is more than plenty for an entire day's budget including hotel, good, transportation, and entertainment!
More significant than the cost (at least to me) is the giant hassle. You have to physically go to the embassy (which is only open while most people are at work) surrender your passport (which means no traveling for you) and then wait 3-5 days for your passport to be returned. And this is the process for someone like me who lives in a major metropolitan area with easy access to every embassy in the world. The pain and expense just increases for someone outside of New York who has to pay to FedEx the application and passport back and forth.
I'm not sure exactly what the Vietnamese national security is onto that others are not (the Thais, for example) but I can tell you that I'm a lot more likely to visit places that make it easy for me. Maybe some countries are doing a really serious background check to make sure they're not letting in any ne'er-do-wells. Maybe they're just being a major pain in the ass or trying to extract more money from citizens of rich nations (Argentina does this to the US as a quid-pro-quo, although it just recently dropped the rquirement.) I have a lot of travel coming up this year and a lot of it won't be pre-planned. I can say for sure that I'll be choosing which countries to visit on what looks cool and what's easy.