Is there a need to fiddle with what apparently is perfectly working and is serving the need. Well for one the i have choosen a format, XML, unlike the original manuscript which was written in word, in this case has the advantage of source being one and output can be in various format. That is if the source is in XML, it is easier now to convert into HTML, PDF, RTF etc. Also to prove to the sceptics that DocBook is very much suitable for large production quality projects, not that this is the first effort, in this case an entire book has been marked up in XML.
Infact why XML indeed? XML -eXtensible Markup Language has been able to do justice to a large extent to the hype. Maybe having a watch body like w3.org to monitor has been advantageous; unlike HTML which lacked a formal monitoring, ability to extend, a weak structure and no support for validation, XML has all these and more. It is a system-independant, vendor-independant and has behind it the proven experience of SGML implementation, XML being a subset of SGML. I concur with Tim Bray's reported comment that it is ridiculous to use an application like MS Word, Quark Express etc.for writing text which will be stored as a binary and proprietory format therby bloating it considerably. And unlike HTML which has about aprox. 50-60 pre-cooked tags, with XML one can make up one's own. Infact this facility of having one's own tag will make it very, very useful in the long run. And the inherent factor that XML is all about content and nothing to do with presentation will be its greatest strength for years to come. The presentation part is taken care of by Stylesheet or FO or some such thing.