I agree, also Jamie's one is coherent to what the Filechooser does.
I think the rationale here was that you were supposed to first click
on a bookmark on the side pane, and *then* use the pathbar. The
bookmark bar would then act like a re-rooting tool for the path bar.
If you put the path bar above the side pane, this hierarchical
relationship is lost or inverted (but the path bar is still useful, of
course...).
FWIW, path finder put the path bar on the right of the side pane
(http://www.cocoatech.com/images/browser.jpg).