I remember they gave an interview before the show in Bucharest (March 1998) and Page was asked about the not-so prominent guitars on the album: his reply was that it was intentional, they wanted subtlety. He also agreed with the interviewer that they looked for a symphonic sound on it. They both (P&P) referenced Brasil as a strong influence.
I like the maturity, the subtlety and the honesty of this album. I like to think that Page used to live in Brasil at the time and dived a bit more into the black music from there. This is how I took this album. I would have been veeery disappointed if they had made No Quarter II out of this. They've never repeated themselves.
(on the side note, how I wish Robert would repeat SS ...)