Instead of worrying that emoji is replacing competent language use, we can celebrate that emoji are creating a richer form of online communication that returns the features of gesture to language.
A simple idea that's surprisingly secure: drawing your own unlock pattern on a touchscreen. Faster and easier to remember than a password, and much harder to guess or crack.
What can a bunch of people grunting in a lab teach us about our capacity to create language systems? A lot about the gesture- or vocalization-based origins of language.