The REST services work just like the underlying Notes / Domino APIs.  Documents contain summary and non-summary items.  You can build views that select certain documents from the database and contain summary data (and computed values) for each row.  You can read the summary data from a view, but you must open a document to read all the items. 

I guess I don't understand your use case.  Why don't you want to build a view to read the document data?  Also, if you aren't using a view, how do you find the documents you are looking for?

-- Dave