Emoji keyboard shortcuts don't work in Messages

On many applications, typing certain keyboard shortcuts for emojis automatically inserts the desired emoji into what I'm typing. For example, if I type :) it automatically becomes a smiley face. I could have sworn that this used to be the case in Messages, but whether I am right or wrong about that, it doesn't happen now.

Am I missing something? It's really a pain to have to click on the smiley face in the text window and then choose the emoji that I want. Is there a way to have normal, everyday keyboard shortcuts for emojis automatically convert into the desired emoji, as happens in other applications?

—Mark