Okay, the way’s I see it there’s very little, if ever any, reason to go to a swamp. They’re not even particularly dangerous once your character becomes marginally competent, or acquires a reliable weapon like a repeating crossbow. They’re just… there. Now, one thing I also noticed was a lack of salt water in the world, which is strange because New England has large enough salt marshes to be mentioned by name in the generalised wikipedia article on salt marshes. I checked. Now, I don’t know about you, but I think partially stagnant pools of salt water might make it occasionally useful to make runs into a deep swamp with a jerrycan in one hand and a shotgun in the other. If only so I can keep making jerky without needing to constantly raid labs.
Doing so would also lay groundwork for larger bodies of salt water, which could present a greater challenge in the long run, by making sources of fresh water less readily available. Still, some reason to even consider checking out a swamp. As it is, they’re basically a dead zone on my map. Not dangerous/annoying enough to avoid, like blob pits, just… there. A vast expanse of ‘nothing to see here’.
tl;dr: Swamps are useless, so give us a renewable source of salt water.