In a society that is increasingly less centered around reading, unused skills will atrophy and replaced with other things. It's not like the underlying genomics to execute the entire human spiel are getting better in step with societal change. Something's gotta give.

Furthermore, and despite my own inclinations, I have a hard time looking at literacy as an efficient delivery mechanism. In fact, I suspect the amount of time we spent reading for anything other than strictly pleasure will look fairly silly before long (at societal level and a humanity timescale).

In part that seems almost deliberate: Most of the "important" writing, to this day (and even though there has been some push back), prides itself in being fairly exclusive. Well, there you go.