Aside from Apple's shitty response to the brute force vulnerabilities discovered here, I'm also annoyed that Apple isn't nearly as paranoid as they ought to be about the security of what is likely to be the #1 hacker target in their system.
Instead of using a 6 digit 2 factor key, they could easily use 12 character alphanumeric key. That's (20 + 10) ** 12 / (10 ** 6) = 500 billion times harder to brute force. And honestly, is having to type 12 characters such a burden for the exceptional case of a password reset? I don't think so.
Building secure systems is hard, I get that. I've made dumb mistakes myself. But Apple's iCloud contains people's locations, their photos, where they live, their email, notes and other secrets, and iCloud also circumvents all Apple's on-device encryption. It's fundamentally a system that sacrifices security for convenience, and it really sucks that all the real and serious security efforts made by other teams at Apple are negated by iCloud.
There are many people, myself included, who use password managers and who will never ever lose their full disk encryption keys, passwords, or recovery keys. I don't want backdoors. I don't want forgot-my-password systems. I want to opt out of all of it.