Unicode is an international standard for encoding written languages. It supports a very large, but finite number of characters. Not all writing systems have been incorporated into Unicode yet, and work continues to make a truly universal system for encoding all written language in computers.
Unicode is one of the great legacies of our time. It is built to last as long as human civilization itself. If humans still exist and use computers in ten million years, they'll encode their writing in Unicode.
Some years ago, a bunch of Japanese guys decided that what it really needed was a pictographic representation of poop. Since then, there's been a proliferation of extremely culturally-specific iconography added to (I would say, polluting) the Unicode space. This is unsustainable. We have languages for a reason--we combine words to shade our meaning. The meanings of emojis are both too specific to deserve their own Unicode characters, and too broad for Unicode to support all of the possible things you could want in an pictogram.
Maybe in 1000 years nobody eats hamburgers. Why the f**k do we need a hamburger emoji? Why does it look like a hamburger from Japan instead of the US? Because if you add all the things that you could possibly want, Unicode will run out of space.
So screw emojis.
(Note, I'm not against pictograms in general. If you come on here saying that "yes there are emojis for those things, I downloaded them on my iPhone" that's because you don't know what an emoji is.)