There was a collision on a runway a while ago that we passed around the news article for, because it could have very easily been prevented by features we had, but were not certified for the airframes that had the collision. It's understandable that we want to ensure that the new glass works just as well as old instruments, but it's frustrating when customers very clearly want functionality that we're not allowed to provide.
I believe there are efforts underway to change the rules to avoid this "making the perfect the enemy of the good" effect: http://en.wikipedia.org/wiki/Small_Airplane_Revitalization_A...
For instance, laptop PCs running Windows and iPads are certified for EFB use now (I would assume for approach plates as well), but I'm not sure what the limitations are, or what certification level that is.
Btw, what did you work on in avionics, and what made you move to a different area of work?
And in the air, you have a little more time to look at the instruments without risking crashing into a meeting car or driving off the road. I suspect (hope) that the current trend with touchscreens in cars will be a fad, and that manufacturers will realize that some features (climate control etc) are best implemented with traditional controls.
It's sad when my 10 year old car has a UI on that part that allows me to use it without taking the eyes off the road.