I just wrote an insightful article about the secret that directories don't want you to know. It explains why submitting your site to hundreds of directories is pointless and completely Un-useful. Click Here to read it. I really hope this article saves you time so you won't have to submit your site to many directories. I posted this already in the directory section and apparently it is a topic that the owners don't want you to know about since most of them argued my point and made completely harsh posts that were not constructive criticism, so please don't follow their example, If I overlooked something please let me know. I am posting this in this section as I want more opinions preferably from experts in the SEO field.
You article actually doesn't cover the main reason why directories are not useful (not useless). One thing is many major search engines devalue certain directories based on either they sell text links or run automated systems that in a sense create a link farm; however this is rarely an issue the main reason the value is usually low is because of the massive outbound links originating from the site\web pages. Also, something people always forget to do is check to see if their category is even indexed in the search engines, 30% of the time you'll find the section your submitting to isn't even indexed in the search engines, therefore spiders either don't like the web page, can't find it due to improper link structure or just don't visit it often enough.