No, making it a default makes sense. Users will not get mad if they get a warning telling them email support will no longer be possible. Alternatively you can opt with giving them a recovery code by which they can contact support or with which email will be enabled for an account when the user forgets their password. The only time you can't turn on email on your account is if you lose the password. Email is not secure, a user that has their login compromised is very likely to also have their email compromised. Moreover, if their email is compromised this completely silly dependence on email will get their account on your site compromised as well so you should be using a non-email means of authenticating users for support or account recovery!!

Email must die. No buts or ifs. It must die. You are a poor or ignorant engineer and architect if you build new things that depend on email in 2020.

If you give the most mediocre hacker 100 emails of users of your service that depends on email for account security, I am confident he/she will compromise at least a 3rd of accounts.