Hadestown was in a unique position because they didn't even release all of the MP3s at the same time. They released them in batches so that they could take more time to work on the album. I think the final batch came out a couple weeks ago. So they couldn't put out the CD until all of the tracks were done.
I just pre-ordered mine. And I'm quite happy with the full libretto being there. If every word of it is there, then a synopsis is less essential because reading the libretto will make clear what is happening. For something like Tootsie, which doesn't need to include the whole libretto, then you need the synopsis.