It's purely a question of finance. I know (slightly) a couple of the people involved, and they are very keen to get it all done. Not just the sea songs, of course, but the whole corpus. Plans for a print edition were dropped for a time, but funding has now been made available for a team to start work on it: the British end is based at the University of Sheffield and the American at the Library of Congress, which owns the collection.

The catalogue can be seen at The James Madison Carpenter Collection Online Catalogue

Transcription from the wire recordings in particular has proved very difficult in the past; Bruce Olson outlined some of the technical problems involved (here or on one of the discussion lists; perhaps both). Digitisation should enable much better results.