BBM: Unless you're suggesting something else, it may just be because they are wetlands. Once the most readily build-able lots are gone, and RE values have risen enough, it becomes affordable to pay the extra money associated with salvaging less build-able lots. Of course, there are lots of private reasons that can be associated with land suddenly becoming available (like the death of old-time farmer or a property that's been tied up legal drama over an estate finally being settled). I've seen the same thing happen around here tho re sensitive environments: Once the prime property was taken, builders started looking at steep slopes.
The developers shouldn't be allowed to build in these areas-even if you don't care about the contamination that results from building in these sensitive areas, it isn't right that they should be allowed to fill the wetlands and then build. That water doesn't just disappear, it moves over to surrounding properties and changes them forever.
I wonder just how wet these wetlands are-could there be enough water there to hide any of the missing Staten Islanders?