I was thinking about this and I think if we were talking about second hand smoking in the 60s this forum would have similar replies. (i guess submitted via punch card)
Person A: "I love shag carpeting and this new band called the Beatles, but is it ok to smoke around my kid?"
Person B would have answered, "well I do and no harm done."
And truly, many kids were raised in houses with second hand smoke who have no noticeable side effects. But at the time, the pediatric associations were recommending no second hand smoke for babies. And now that everyone knows that cigarette smoke is dangerous and we've had a generation of people aware of it, no one in their right mind would disagree. Even if they thought it was all just overreaction. I, for one, would have wanted to be one of the parents who aired on the side of caution.
This is a similar issue. It may be okay to have your kid play angry birds at 5 months (but there's no way they'd break the top 100 on game center) and there is lots more research to be done. But considering the iPad is a year old, wouldn't you hope everyone aired on the side of caution? It's not like the other 4 year olds will have these great IT jobs and your 4 year old is stuck working at the 7-11 until he finishes night school. If a kid can figure out an ipad at 2 it doesn't show you how smart the kid is, (though they may very well be quite advanced) it shows you how easy an iPad is to use.
Now if your two year old can replace the battery in an iPad. THAT'S something to be proud of.