Is email based 2FA a good idea? (twilio.com)

This is not really 2FA. SMS 2FA is better than this. TOTP (or HOTP) or a combination is much better. FIDO U2F is way better. There are much better solutions out there with usability as well like passwordless barcode scanning by vendors like SAASPASS.

Disclosure: work for an SI that implements IAM solutions that include SAASPASS.