In addition to creating aesthetically pleasing pages, they must also structure their documents in such a way as to maintain compatibility with SGML-based document management tools that haven't even been created yet. Predictably, contemporary snake-oil salesmen are responding in force, and automated software tools for converting existing documents to HTML, and for generating new documents, are all the rage. Such programs are of limited technical value. Document convertors are typically based on a traditional typographical layout model, and not the structural model necessary to generate broadly compatible HTML documents. It's a safe bet that the converted documents will require extensive structural modification.
Similar caveats apply to page generators.
Happily, HTML is not rocket science. Re-visioning Creativity These are exciting, frustrating times for accomplished communicators. The rules are changing faster than anyone's ability to accommodate those changes. One key contribution of accomplished professional communicators will be to help shape new definitions of content, structure, etc. Designing documents for the Web requires not only a new set of technical skills, but also a new definition of creativity.