My real problem with this is writing the password with numbers, punctuation and stuff on a mobile keyboard. Feels like surgery even if I'd memorize it.
I use 1P on my laptop most of the time so it's not a huge deal. Everything else on the iPhone just remembers credentials.
I know I can force myself to use a great password for iCloud but my point is that most of the time, I'd go for an idiot password rather than forcing myself. Just like most people.