Aliens find out about "ink poisoning" and get concerned about crew members who write on their hands. -- Anon Guest
There should be no reason for a living being to draw on their own bodies. Data readers are flexible and wearable, they can go anywhere a cogniscent being does. The art of writing in and of itself is a niche for hobbyists, since everyone in the modern era types. Well. Almost everyone. There are niche hobbyists and the occasional fanatic who just... like to do things the old-fashioned way.
Niche hobbyists and fanatics who share the same love of pokey little shops that seem to contain three hundred versions of the same thing. Those who fund them can spend hours making decisions about those things, no matter how seemingly identical they are to a novice. One such place has, for instance, a million seemingly identical pens. All of them, no matter the construction, the content, or method of ink delivery, are subject to one question:
"How's this for writing on skin?" Apparently because those who love pens can't be bothered with paper or paper substitutes. The most likely reason is that people will forget bringing a notebook, but can't exactly leave their skin just any old where - swear though they might that they would forget their own head next.