There is a clash between our paper-based tradition of visual iconography and our use of computers. For centuries, if you wanted to write a visual mark — a symbol, or logo, or indicator of any sort — you expected it to be immutable.
But if we phase out paper as a primary means of visual communication (and there is good reason to believe we might), then that expectation of immutability will eventually shift. A “written” icon will no longer need to be fixed in appearance, but will be able to vary over time, depending on some changing context.
Whether we are looking at a logical AND gate, or a stop sign, or a right-facing arrow, we may find ourselves no longer satisfied with a particular appearance. Instead, we will expect that symbol to indicate some current state, and to change in appearance when that state changes.
Such expectations are still low, because marks on paper are still the cultural norm. But once paper starts to disappear from the equation, all bets will be off.