I suspect some people have either never heard of emoji - could be old or young, not sure - or simply didn't think they would use it before these kinds of featur

I suspect some people have either never heard of emoji - could be old or young, not sure - or simply didn't think they would use it before these kinds of features came along. Outside of Apple nerd (and broader HN) social circles, the awareness of this is probably much smaller than we realize. After all, even with social networks, we still haven't convinced everyone that the "at" username construct is a useful way to get people's attention online.