My main argument would be I don't understand multiple cursors unless there's a lot of identical lines which need prefixing or suffixing (and regex can do that).

My main argument would be I don't understand multiple cursors unless there's a lot of identical lines which need prefixing or suffixing (and regex can do that). Vim lets you select stuff before acting on it, so "wanting to select stuff before acting on it" doesn't seem like a good reason to leave Vim. Although in practise I rarely use that.