Ursa- Er, yep, that 'slim volume' thing... not so sure, now. He said that's what he wanted to do--bear (geddit?) in mind that interview was conducted before he set off on his first draft. Like children, novels never grow up the way you planned them to do.
That does sound a more likely situation. And I'm sure I could bear reading quite a few hundred pages about the various heavens and hells, as long as they are a clear part of the story and not just add-ons**.
** - I didn't particularly like Look to Windward because of what seemed - to me, at least - to be the author's throwing in 0f descriptions of various locations because he had thought them up and saw them as "interesting". Trouble was, they put the plot on hold. (Oddly enough, I think I'd have been more interested in these places if there hadn't been a plot, if that makes sense.)