XMLTree presents a tree structured view of XML files, instead of a Document Object Model view.
XMLTree was released starting in 2002. It is difficult to tell when xmlread() was first released for MATLAB: it dates back to at least 2002 but it is difficult to say how much earlier (difficult to find the historical documentation.)
Considering the amount of work that appears to have gone into XMLTree, I speculate that the author of that third-party toolbox had need of reading completely conformant XML at a time when Mathwork's routines did not yet exist or were not yet complete.
