I've seen many people touring on bikes with flat bars, and I confess I don't get it. When I'm riding hours every day, I want postural variety, and riding positions are fewer with flat bars than with drop bars.
Yet the flat bar people don't seem to be bothered. But flat bars don't work for me. I prefer drop bars that are set up high enough so that I can sit nearly upright when I want to. I am not interested in aggressive riding positions favoured by racers. But I do want to alternate between sitting upright, getting low, gripping the bars with palms down or palms up, and more.