The beauty of JSP Tag files is that it lets you basically tag generic markup and then refactor it to your hearts content.
JSP Tag Files have pretty much usurped things like Tiles etc., at least for me. I find them much easier to use as the only structure is what you give it, nothing preconceived. Plus you can use JSP tag files for other things (like the user detail fragment above).
Will Hartung's overview of JSP 2.0's Tag Files is a great primer