Legal directories hold more importance than you think. More than anything else, people rely on internet for learning about trustworthy law firms. They open a search engine and type in the kind of lawyer they need. Now, if your website contained the exact words that the prospective client typed then it will appear in the search results. Otherwise, it will not.
However, online directories appear with almost every kind of keywords because they are better optimized. Hence, even if your website is not rich in keywords, by enlisting your firm in these online legal directories, you stand a good chance of being noticed by your prospective client.