They are common, sure, but you are thinking purely from a utilitarian standpoint.
Trodes pretty much mean you either need a hat/helmet with the trodes inside, or a net of wires over your head. That is fine for gangers, delivery guys, the schmuck behind the counter at Stuffer Shack, and so on. But if you're in a profession where looks are important, then your options are more constrained. Constantly wearing hats indoors doesn't go over well in most business settings, to say nothing about helmets. Even most salespeople in a retail setting can't get away with that. And a trode net will play hell with your hair, so unless you're bald (like that elf combat mage archetype from the SR4 book), that is less than helpful with keeping a 'respectable' image.
And even if a salesperson has DNI, they may use visual hand gestures anyways, because that cues other people in that they're actually doing something, and not ignoring the customer's question.
So while, utility-wise, you are correct, when looking at it as a question of form over function, there's a lot of people who wouldn't be using it.