Sorry - but for all the arguments why this is A Good Thing, it looks less like a security 'feature' and more like Apple dissuading users (especially those who want no part of their 2-part authentication) from using apps that are superior to their own.
And remember, this process means you're not just creating new passwords for your 3rd Party apps, but you are having to buy into Apple's 2-factor authentication and its process. As far as the 3rd Party app developers and their access to our iCloud accounts, well, that horse has already left the barn, because I've already given these 3rd Party apps the access code. And the letter doesn't say anything about changing your master password to iCloud before doing all this. If you can.
And frankly, given the companies' apps I have given access to iCloud, I'm not sure they are any worse threat than Apple is.
Apple tried to initiate this a few years ago and it simply didn't fly then. Daresay they are using currently media reports as 'incentive' to make it seem like you'll be more secure. Not convinced.
May yet end biting the bullet - or, contrariwise, say' screw it' and use other apps and syncing bypassing iCloud entirely.
Thank you well, said Bazza1!
I've just been asked to set up yet another app specific password to use Spark (email) after having to 2FA my login to iCloud on my main iMac again. This will no doubt mean that I will have to set up another password for my iPhone again because I've just changed the app specific password, again, just so I can collect my email. It's getting crazy.
Firstly, I'm not trying to log in on a new device (iMac) which is actually screwed to the wall in my office, and there's nothing new about it. Every now and then I will be randomly asked by my email client to set up an app specific password. This has already been done. About 10 times.
So, this is what has happened.
I've started looking into using Google services. That's right - closing down iCloud. It turns out that iCloud is my main problem.
I can use gmail, calendars, MS Office, One drive with TB of data across users, unlimited full resolution photo storage, notes, reminders, and on and on. It works out cheaper than using Apple's nickel and dime services, and I can buy the google pixel instead of iPhones for my business. I can properly utilise family sharing with Office 365 and google photos.
The only service I have to/want to keep with Apple is Apple Music which runs on android anyway.
I've been an Apple user since whenever, and I'll probably continue to use MACOS, but I didn't think it would be something as obtuse as iCloud that would make me think again about that.
Basically, my modern computing needs are more about services and cloud storage and software etc than they are about hardware and OS. Microsoft and Google are killing it with software, machine learning and integration of services and even hardware. Apple aren't competing any more for me. They have nice shiny things, but without iCloud connecting everything together properly they're pretty much redundant. It's easy to fix iCloud, which makes me think that Apple just doesn't want to.