Could be a world generation issue, but you can find tons of scrap iron in the mistlands so I dont think it's intended

I've only been to one big Mistlands portion of the map. The others were previously visited prior to the patch and didn't have the new content. I was lucky to find the island that had the queen. But I landed initially in a portion of swamp that was neighboring the Mistlands. It had one crypt in there that was pretty close to the border. It may have more but I didn't go off exploring the swamp.

I think it is a matter of size of the swamp and RNG.