I've found one surprisingly useful aspect of emojis. Emojis tend to be visual representations of actual things or feelings, whereas letters or glyphs are visual representations of a language. This means Emojis are actually one level removed from language, allowing them to be used easily across languages by people who could struggle communicating.
Texting or IMing someone who speaks another language and adding emojis actually makes it significantly easier to communicate. For example, a messaging conversation at work can go much smoother with someone from S.A. who has poor English if you add smileys every so often indicating your mood. It may seem unprofessional, but it can actually provide information someone couldn't process otherwise because of lack of familiarity in the language.