The only argument I have against this technique is password reuse.

I do agree that having a long plaintext password is secure enough (eg, a quote from a movie, book extract, …). For it to remain secure, you should not use the same password twice, which means remember the "trick" associated with each password, and being able the recall it.

This is tedious, and I ended reusing passwords a lot.

For this reason, I decided to use a password manager. I helps me remember the password I use for each service. At first, I dumped my own memory into the password manager. After I integrated it to my workflow, I didn't feel the need to have "understandable" passwords anymore, and just switched to randomly generated ones, because I didn't have to open a random book anymore 😉