See that's when I think emoji shine - trying to convey ambiguity over text. In person a shrug can mean a few things, some of which might be harder to say explicitly, for social or mechanical reasons, and an emoji seems preferable to *shrug or (shrug). I think that disambiguating all of the emojis or even continuing to expand the dictionary so much would make it boring. If the emoji meant the word exactly I'd just type the word, it's much easier than trying to find the right emoji.