If you use Windows, you can use AutoHotKey and add emojis via Markdown with this script.
There are cases where I see emojis are useful. For example, in Software Recommendation there is a feature request to have checkbox. Or when the conversation seems to be heated, an emoji can reduce the heat, and the recipient can focus on the information rather than let the emotion overwhelming.
Some other useful AutoHotKey scripts I recommend too: LaTeX, AutoCorrect, Quick Type HTML Tags
<!- This off-topic recommendation is for users who don't know what AutoHotKey is for and be intimidated from trying it. The usefulness of this answer highly depends on their intimidation. ->