We used to do it because dealing with cross-browser compatibility was a pain. For instance, I used to use a 1-pixel applet instead of XMLHttpRequest for AJAX (s

We used to do it because dealing with cross-browser compatibility was a pain. For instance, I used to use a 1-pixel applet instead of XMLHttpRequest for AJAX (slightly before they coined the term "AJAX") and applets for rendering live-updated XML-based diagrams (instead of SVG) in both cases because it simply made things less buggy and less of a pain to support at the time. But that was in 2004 to 2007. But once we've written something, and it works, we're often a little slow updating it to newer tech, because we can't write a paper out of "the same thing I published earlier, but now using SVG and XHR instead of applets". If it still just-about works, there's less impetus to rewrite it.