With the release of 5e 2.4 I'm going through some of the changes to bring the importer up to date. it's becoming increasingly difficult to support such a wide berth of system and Foundry versions. (And will be several days till a version that has much more native support for 2.4 changes is released). The upside for supporting versions is that those folk with older versions or who don't make big updates during campaigns get new features (although arguably, these folk are lest likely to need to remunch things). The downsides of supporting more versions is that the code can get quite messy/complicated, and it slows down development and new features.
I'd love to get your input to help gauge upcoming development effort, and possible support paths.