well for a free directory I dont think they are that important as people will submit anyway because its free, but for paid directories I think its fair to say that people are more likely to submit if you offer deep links, not only that but deep links help the submitter a lot with their seo.
I can understand and appreciate the question. The answer is no. That's why I put traffic as the deep-link motivator in answer #1. But I am among those on DP who consider PR to be of some benefit, and therefore not to be ignored. In my earlier answer, I forgot to add another reason I submit deep links, both to directories and to social bookmarking sites. And that is the fact that it gives me the opportunity to use well-researched keywords in the anchor text of those links to my inner pages.
i don't think it's that much important, but it's a plus and if you can make the mod do it, you've got nothing to loose