Because like you, I want to clarify tone? Emojis don't make you childish. It just helps express the feeling more. "How sad" and "How sad ( ·᷄ ︵·᷅ )" give off different vibes. How are you going to complain but use a smiley emote in the same instance? (。≖ˇｪˇ≖｡)
