In general I agree to @Craig
typically can't be used to make changes to your account
to clarify this part:
2fa in combination of app / domain specific passwords is a good practice to secure your digital identity as good as technically possible atm *) i.e. better than without, but isn't the holy grail.
2fa addresses not only (the most important part) of enriched security level but also making logins easier without a password safe, since you might lower your password 'complexity' (to be kept in mind) while in combination of the second factor (possession) your account security might be improved. (I don't say you should do this that way ;) )
Still: a compromised app / mail password can be used to abuse your account, e.g. opening accounts on other systems or make orders in behalf of you with your correct mail address; even the attacker isn't able to make changes to your password or account details on your Identity Provider in general. You are still able to recover ... if you are in knowledge of an abuse usage.
Still: if 2fa is just on top of a bad password and there are no app specific password, app (mail) security is "compromised" because of false positive safety feeling of 2fa in web; watch out for your provider security settings what is possible, it might be more secure to keep your "old password" ( https://www.xkcd.com/936/ ).
app specific passwords are nonetheless just as secure as the provider generates them. And their advantage is only given, if they do restrict access to a given resource. Providers like "the big G" doesn't make a great job her in my eyes, since the passwords are generated 128bit only with a low entropy (no special chars, etc) and this password can be used for any API without restrictions. The given "application" is only a hint to you, where you do use this if you like to revoke one.
*) as far as I know there are no known RFCs for advanced IMAP/POP protocols that would take mail clients in advantage of 2fa. And I doubt we will get one because of the "big" backward compatible problem of legacy mail clients.