SMS auth has one really big advantage. There is a human run authority one can appeal to if a device is ever lost, stolen, or forgotten, which you might not be able to afford to manage yourself.

It also makes spam accounts harder to make.

I think it should always be an option until something with similar properties arrives(Like a YubiKey with the option to have them keep a key on file and reorder, with their agents somehow making sure it's you).