Absolutely. There are some areas which are, by default, are more difficult than others. I don't plan on taking the time to add such legends throughout the world, especially procedural ones. I would mostly scale the difficulty by biome and distance from the center. That way, the Tundra and Desert would be among the more difficult areas to traverse. Of course there would be pockets of very hostile areas scattered about, like Swamps and such. Good idea though.