XML is doubtlessly an imperative exchange format. Now the questions are- can it be considered as the best format for authoring? For complete text content should it serve as the official storage format? To what extent of upstream should it be integrated into workflow?
Before starting to ponder over, have a look at the books for a while. Publishing industry has made EPUB and MOBI as standard format for electronic delivery. This helps publishers to seek only fewer options for official source format. Though most publishers are yet to adopt HTML, this mark-up language also is crucial when it comes to book publishing as per reputed Indian companies. Most advanced and progressive publishers such as O’Reilly are now embracing HTML5/CSS3 workflow, which avails a rich authoring as well as editing experience. Above all it helps you a hassle-free and swift electronic and print delivery without any long complicated processing or conversion.
Why companies offering XML file conversion are being hired? Perhaps, it is because people have become accustomed to it and they are not willing to think of any other option. However we can enlist some notable benefits. It is software/platform independent and so is HTML. XML allows the remixing and management of content towards node level which is not that useful for journal articles. It also permits transformation of the content to numerous formats including PDF. The same can be done using HTML/CSS3 also.
To mention the downsides, XML workflows is costly and when it is about conversion, the process is time consuming as well. Another issue is with the learning curve.
So, in a nutshell even though HTML seems to be a better option, the positives of XML should not be overlooked as well. Being an experienced service provider, offering various types of conversion services, we would really be happy to alleviate any types of doubts that you may have in this regard.