Check out this article that just popped up on CNN:
http://www.cnn.com/2017/05/29/design/emoji-digital-language/
Some key quotes:
"Emojis have become, without a doubt, a design classic. But how effective are they as a communication tool?
Over 6 billion emojis are sent on a daily basis, with over 90% of the world's online community making regular use of them."
"So if emoji isn't a language, what is it for? Some see emoji as little more than an adolescent grunt, taking us back to the dark ages of illiteracy. But this prejudice fundamentally misunderstands the nature of communication -- and in so doing, it radically underestimates the potentially powerful and beneficial role of emoji in the digital age as a communication tool.
All too often we think of language as the kingpin in our everyday world of meaning. But much of the meaning we convey and glean in our everyday social encounters comes from nonverbal cues."
"Digital communication provides us with an important channel of communication in our increasingly connected social and professional lives."
"We live in a digital age, and emoji is an adaptation to this most recent arena of human interaction."
While this doesn't specifically have anything to do with emoji domains, I think it really does illustrate that they are the natural progression and evolution of communication on the internet.
I think that even just their language-less ability to convey information and meaning, is worth quite a lot on it's own, combine that with a website that has multiple localizations, and now you have a real tool to connect with customers from all over the world with just one web address. This is really powerful stuff.