1) The emoji has several possible interpretations/meanings depending on context, such as "I don't know", "I don't care", "indifference" or "shrug". There's this saying, "a picture says a thousand words". It applies here (nobody said the words couldn't be a few words in hundreds of different languages ;)).
2) The emoji generally does not require translation to different languages. It isn't universal, but its more accessible, and some emojis are certainly universal (such as :) which is a facial expression my 3 month old understands).
Really good point. I don't find watching a keynote speeches about emoji at all exciting, either. But I work on a mixed-language engineering team with a lot of (extremely smart, highly literate) people, and we use emoji all the time.
Whether it's cold-sweat-face or thinking-face really helps me understand the nuance of my colleague's Japanese comments (which, btw, as a native English speaker with only fair Japanese ability, gives me a free opportunity to experience 'basic or lower literacy').
I know that adding emoji characters helps them in the same way, so I use them frequently.