DTD/Schema resolution has improved. SGML applications tended to be rather helpless about where to look for the DTD, with each vendor having a different idea of where the right place was. Catalogs fixed most of that problem, but required care and feeding, and Owners were sometimes careless about naming, spelling, and punctuation. XML Catalogs are an improvement, and with the Public Identifiers now less used, most software seems to look in the document folder for the System identifier unless otherwise instructed; or at least it asks for it instead of crashing with an error message.
There is more consistency. The web interface paradigm, which was still in its infancy in 1995, is now the dominant method of interacting with general users — people, even non-computer-users, are expected to know that you click on things to see more — in the same way that office software is expected to work like Word and Excel. Breaking dominant patterns like these needs extraordinary changes and extraordinary benefits, and the new paradigm of everything being clickable, and not necessarily coloured blue and underlined, is an opportunity to ensure that the underlying XML is used for consistency.
The move to using XML as the storage format for both Open/Libre/Neo Office and Word has been a sea-change in making documents programmatically accessible
The creation of XPath and XSL (both T and FO) has brought about huge improvements in expressing addressing and programming transformations
The lessons learned in usability from end-user interfaces like the Panorama/Synex/Citec-type navigation and stylesheet creation windows mean we now have much better facilities for creating in-app navigation and styling tools
There seems to be far less reinvention of the wheel now, in that many more applications re-use, or build on the shoulders of, existing schemas and DTDs, rather than inventing new ones every time. Writers and speakers have constantly warned about the risks of corporate hubris in writing everything from scratch rather than adopting or adapting a close-match common vocabulary and structure — while at the same time extolling the virtues of modularity and extensibility ???.