The basic reasoning behind our Export API is to provide customers access to potentially large sets of data that would otherwise be difficult or slow to retrieve with our standard API. One hassle with the standard API is that to support some of the things it does, data that we are returning has to be buffered in memory before it is returned. As a result, very large data sets can blow out the memory on our servers and destroy the API call making it. No bueno.
What about paging?!? Paging is not supported at this time and very well may never be. Anyone who has used MySql (and plenty of other RDBMSes) knows that paging through a huge result set can be slow, especially when you start joining lots of tables. Paging is also a pain to do when you just want "everything," which is the point of this API.