If they teach crabs how to read, there’s a risk their society will advance to the levels seen in Carcinia, leading to a downfall of overcleanliness as king camtcha bleaches the city against the advice of his wizards, throwing the entire old ocean into disarray.
My understanding is that they also aim that way to reduce moving parts - since knobs, buttons, and switches are more likely to fail after 5000 uses. That, and they can update touchscreens to do whatever they want differently, like serve up ads.