Comment by markhemmings

It was a larger number at first, but try remembering say 10 words in a row over a long period of time; most people find that difficult. If hashing is implemented properly (i.e. is slow with a large number of iterations) then passphrases shouldn't have to be that long. And if it isn't, then pretty much anything you use will be as bad as each other (Some people are still using MD5 for example!!) :)