PXSL and related languages are indeed interesting approaches to "clean" up the source code of XSLT stylesheets. But the problem remains: you take one look at it, and you still don't understand that much. You still have to roam through the source code to get answers to: which template calls which template;

are templates located in other files; etc. This are questions which aren't answered immediately. Although I am aware that probably no visualization or any other method can make a complex stylesheets understandable at once, just making the code more readable won't solve the problem. BUT it is one step to it, that is true indeed!