We are talking about RSA though, so there is a fixed character length and it isn't meant to be remembered because your private key is stored on disk.

Yes the word method is better than a random character password when length is unbounded, but creating secure and memorable passwords is a bit of an oxymoron in today's date and age - if you are relying on remembering your passwords that likely means you are reusing at least some of them, which is arguably one of the worst things you can do.