I work on multiple websites, each having an "images" folder.  It would be great
to be able to either rename the folder bookmarks, or alternatively, to add a
comment to the name that could be, for example, displayed in brackets next to
the folder name.  I realize that such an option could create confusion with
users thinking that rename means literally renaming the folder, so perhaps the
comment option is better.  A third option is to display the containing folder as
this additional information would be sufficient in most cases to differentiate
easily between like-named folders.  For example it might display:
..\websitename\images

I guess you could include the drive letter as well, but perhaps that's not
necessary.

I don't know about the difficulty of implementing any of these suggestions, but
the new dialog with the bookmark feature is definitely already a vast
improvement over the old dialog.