It is not. Ten or more years ago it was important because search engines used it as a seed database to find new sites. Search engines no longer need it because their search methods for finding new sites have greatly improved.
DMOZ has a history of being plagued with corruption and is no longer important. Besides that, it is very difficult to get a listing today.
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -- Benjamin Franklin