They already tried that, don't you remember the 90's with the silly motorized belt attached to the door instead of the frame of the car? Seemed like a good idea at the time...until they figured out if the door was ripped off in an accident it would take the passenger with it. Opppsy.
Anyway, the defrost thing is reasonable. People are too stupid to turn it on themselves and defrost isn't very effective when it blows moist air on the inside of the glass...it just fogs up from the inside while your trying to clear the outside. If they didn't turn on the A/C people would just complain it didn't work. I like the one-touch solution personally but I do understand your point. I used to leave it on defrost/floor because I wanted heat up top, just not blowing in my face.
As for the GPS system....there should definitely be a way to unlock it because a passenger can always make changes while you are driving. For example, while enroute you may be interested in stopping for lunch. Without stopping in the middle of the highway, how can you find where the closest restaurant is?
Now if they were really smart, they'd tap into the passenger airbag sensor (the one that determines the weight of the front passenger to see whether it should deploy the airbag). If the sensor doesn't pick up anything, the unit is disabled while driving. Throw a pile of books on the passenger seat and now the pile of books can choose a new destination...ahem I mean your passenger