I respectfully disagree. I know they don't necessarily pass loads of link juice but some of the paid directories don't have all the millions of spammy links to spammy sites in... because they're paid. Some are very, very cheap too. I know most are rubbish and not worth squat but there's still lots which are cheap and do pass link juice which far outweighs the cost.
Also the paid ones add you much faster... and if you want a diverse backlink profile it's worth getting a bunch of directories in there as well as your other link types... rely on the free ones and you could be waiting forever for that.