Yeah, and I don't even mean you necessarily have to be a world traveler. Your dollars, or euros, or rupees, or whatever, will be competing against those of people from around the world. If you are consuming entirely on a local level, then no problem. But a dinner at a world-class restaurant (no matter the locale), or a BMW, or a bottle of 1st growth Bordeaux, or a vacation in Las Vegas or Greece, will have a price not affected by local salary adjustments.
So, the local quality of life in Bentonville might be great (low cost of living, low average salaries), but if you ever want that car or bottle of wine or ski vacation you'll be competing with people earning dollars in San Francisco and New York (high average costs, high average salaries) - not a great feeling.. To think of it in reverse, people in SF and NY might not "feel rich" because their discretionary money doesn't go as far in those cities, but they feel like kings when visiting lower cost locales - which is pretty much everywhere else (I know there are even more expensive cities around the world).