I certainly don't see search engines providing exactly the same service that I provide yet but they're getting closer with maps and local results.
The same reason I built the site over ten years ago still exists today, to promote new sites and services. A new site goes online and is still buried in the search engines yet the directory shows the site immediately to a focused audience looking for those types of sites.
Yelp is a prime example of how directories can evolve as review sites opposed to stagnant Yahoo or DMOZ and Google is well aware of the importance of the data some of our directories contain and the services we provide which is why they now use Rich Snippets and Microformats so that Google can take advantage as well. [webmasterworld.com]
That's how you view it today as SEO related but that's not how it came about.
My directory was built with reciprocals before search engines existed because links are how you found your way around the web and directories were the hubs that linked it all together.
The TRUE irony is that people now decry those linking methods that built the web in the first place and would willingly roll over and give all the control to the SEs when in fact the SEs couldn't have assembled the web in the first place with our original directories that organized it from the beginning.
Directories ruled the web, and to some degree those that evolved still do as evidenced by the emergence of Rich Snippets [webmasterworld.com], so we're not willing to go silently into that dark night just yet.