Fair points seancron. Wirify is already skipping quite a few HTML elements in its processing, however it certainly works better on some sites than others. I've found that proper 'semantic markup' also gives better results than old school table-based layouts for instance.

One of the earlier prototypes let you control the 'level of detail' in the wireframe: http://www.youtube.com/watch?v=wuKJVZRDjRo We've decided to ditch this idea for the time being though due to the extra complexity.