I'm not sure that I relate all the lack of simple knowledge among kids to computers; I think it's in part due to our education system. I am an educator, and it's not that teachers have stopped teaching and sit around and pick their teeth. Actually, it's just the opposite, but I think it's backfired.
At some point, we decided we were falling behind in education in this country; therefore, we had to make it more rigorous and make the content more advanced. In doing that, the states and feds handed down a curriculum that leaves out the learning of basic skills that are building blocks of higher learning, or just good stuff to know. When grandparents look at a student's second grade work and say, "We didn't do that until we were in 7th grade," they aren't far from reality.
Here is an example I remember. When I was in 8th grade, we spent a chunk of time learning to identify the states on a map and knowing the capitals. The teacher would discuss interesting items of the states, we would take turns identifying them on the big map, and taking individual identification tests. We repeated a similar process in high school. These days, activities like that would be considered a "waste of time" because it is only addressing the "knowledge" level. According to the experts, learning the states these days should be embedded in a higher order activity, but I feel that what once was common knowledge is being overlooked today. Students can explain Einstein's Theory of relativity, but aren't sure where 3/4 of the states are.
When I was in high school, basic math classes still existed; it was things that would be used in everyday life, but no more, that would be a waste of time. My 16 year old daughter said one of the top students in her class had trouble with long division because it's something that isn't addressed anymore once it is initially taught in elementary school. I'm sure he could have blown the Algebra class away in his sleep, but a long division took him down.
It's even been handed to students with disabilities. For students with an IQ of 55 and below, it's no longer acceptable to just focus on teaching them functional things that could help them in real life; they are also expected to address regular standards which will have no impact on their life that I see.
So, I think our schools are partly to blame for the lack of common skills and knowledge that our kids seem to lack, and it's not the individual schools fault; anymore, we have to teach what we are handed.