When I played EQ, I think they were the ones who made the big atlas for it, when....Planes of Power?... came out. If I recall, it actually was pretty useful- it had very well fleshed out maps, along with several pages of information relevant to the zone.
If it had all quests in the zone, and where to get em? You bet I'm buying it.
Sad thing about MMO books is that they are almost never complete. All the Prima EQ Strategy guides were a joke- they openly admitted incomplete information in the book- they didn't want to list creature stats past level 20. Want. Hell, all it really was was a more long winded version of the manual with "Veteran Players" writing a short one page essay on each of the classes. Yippie.
Another issue that might arise is new zones- what happens when another one comes out, as they so often do?
I think if one on the level of Brady's EQ atlas were to be released, I would happily buy it- it was fun to look through, and it was well presented. Sides, eventually, with the massive popularity of this game, they are bound to release an updated version in conjunction with the expansion(s).