all-in-one devices are just that. People have yet to modify their expectations to fit reality. Eg a camera phone will never match a dedicated camera, but then how many digital camera owners use their device to its full potential.
Personally I use a Nokia N80 as a radio, MP3 player, sat nav, camera, PDA and (of course) as a phone - I've been using it like this for 6 months and all it really lacks (for me anyway) is sufficient storage space.
Yes the camera is limited, but then so are my photography skills.

"people who may also have to live with the unbearable conscience of possibly having severely injured or killed someone else"

(personal anecdote warning)

You're assuming the driver has a conscience - the guy who hit me head-on didn't. He finished his call whilst dragging my motorcycle to the side of the road, then moved his 12 ton truck out of the way to prepare his story to the cops.
Luckily forensics proved me in the right, but he was never punished for using a phone while driving. For all I know he's still driving trucks through London whilst on the phone - scares the hell out of me anyways!
And yes I use a phone in the car, but only witha complete handsfree setup, and only to receive calls. Any time I feel like making a call I remember the 2 years of physical rehab I went through, and pull over.