This article has shown that with either MSXML or JAXP it's relatively easy to perform XSLT transformations using DOM documents as source and result. Of course, for most applications the process of building in the capability to use one of several different stylesheets, and not just one hard-coded stylesheet, involves more code than what's presented in these simple examples. However, if you're already using the DOM, the basics of performing XSLT transformations are fairly simple. Any application that might need to produce or consume a variety of XML formats is a prime candidate for built-in XSLT support. I'm sure that the extra development effort will be justified by the convenience and efficiency that build-in XSLT support provides to your users.
The program source files, sample XML document, and XSLT stylesheet can be downloaded in a zip file.