I suspect that they are still trying to get the paradigm shift right in their own heads and what you are writing is INK hence a PEN!
<mindless technical ramble>I've noticed with students and our headmaster who've been testing out the tablets we have that this is really a significant paradigm shift. I'm betting that for most people learning to fully utilize a tablet as tablet is as disruptive as going to a computer in the first place is. So many computer skills to unlearn. (I liken it to snowboarding, where a rank beginner actually has a less challenging learning curve than an experience skier who has to unlearn all of his skiing behaviors.) The same could be true for the developers. </mindless technical ramble>